I agree with Leopold Kohr ("The Breakdown of Nations", 1957) and his friend and student E.F. Schumacher ("Small is Beautiful", 1973) that "bigness" itself is the problem. You can't have "mass society" without having big business and big finance and big government, and these centers of big money and power are magnets for wealth, power and status hungry individuals who strive energetically and often ruthlessly to get their hands on these levers of power. So I agree with Codger that we cannot reform "their" big systems, because "they" will always do whatever it takes to maintain their wealth, power and status monopolies within the systems that they built for that purpose.
These rulers own and control all the levers of power, especially the mass media and the education systems that brainwash the population and render them incapable of understanding what is happening, and make it impossible to counter the propaganda with equally trumpeted truths. The masses respond to emotional appeals, not reason, which makes "public opinion" easy to manipulate by slickly professional and power serving mass media propagandists. We have the internet, but I would suggest that we only reach intellectuals who, as Plato described in "The Republic", are interested in observing and understanding but want nothing to do with "government" and are certainly not going to engage in open warfare with the ruling powers.
Most intellectuals sell their minds for money in service to the rulers, as far as that goes. For example, listen to or read some neoclassical economists bamboozle themselves with absurdly surreal economic "models" that "justify' the status quo. Money, banking and finance DO NOT EXIST in these laughably unreal model worlds with barter economies: there are just producers trading their surplus outputs with each other, as Adam Smith idealized over two centuries ago. Neoclassical economics is the dominant paradigm that has been taught in universities, swallowed hook, line and sinker by business journalists in print and TV media, and applied by economic policy makers for the past 6 or 7 decades.
These "economists" are the modern priesthood spinning an alternate reality that justifies the divine right of plutocrats. They are the "experts" who hold all the high positions in the academy and the media of public opinion formation. They have always been countered by "heterodox" economists who accurately describe the real economy and understand how it works, but the real economists are vastly overmatched in the power structure by servants of the orthodox economic belief systems.
So frontal resistance is pretty much futile. Or like in the case of the French and Russian revolutions, the people rise up and destroy the old rulers but some new tyrant simply comes in and picks up the reins of absolute power that were dropped from the dying hands of the old tyrants. In place of Louis XVI and Czar Nicholas, you get "emperor" Napoleon and "comrade" Stalin. I think if there is going to be a solution it is not going to be a mass movement but rather individuals moving out of the system and setting up some kind of sustainable life on their own and in smaller communities.
Rob has noted that there is already a widespread "transition town" movement, relocalizing, rebuilding community: small, local, sustainable solutions. I think that's where the real answers can be found. Ellen Brown is leading the public banking movement, where state or even local governments set themselves up as their own bank as North Dakota did in 1919 with great and enduring success for that state. Typically 40% of the total cost of public infrastructure is the interest costs on the financing, which is typically handled by a large Wall St bank. A state owned public bank can perform the same functions and save the public 40% of the cost. In other words, you can build almost twice as much infrastructure for the same amount of tax money simply by paying the interest on the financing to yourself instead of to a private banker. It should be a no-brainer, especially in light of North Dakota's almost century of successful example, but there is strong resistance and propaganda emanating from the parties who would lose from this change: big private bankers.
We should also be aware how fragile our current globalized economy is, and how vulnerable we are by our dependence on it. When the financial system froze up in September 2008 cargoes sat on docks because sellers could not be certain that the buyer's bank would still be in business by the time the cargo arrived and payment was due. We are completely dependent on the global "just in time" delivery system to deliver our necessities of life. Money is the nervous system of the economy, and if the nervous system fails, the economy stops moving. That almost happened in 2008, and none of the underlying monetary problems have been solved in America or Europe.
The whole world uses the same bank-debt money system, though some nations have either total (China) or partial (Germany, Japan) publicly owned banks alongside the private banks. Public banks are as sound as the nation itself, so unless the political administration chooses to let their banking and money and economic system fail, it can be propped up to keep it functioning. Germany no longer controls its own money, as it has adopted the euro which can only be created by the supranational European Central Bank, so Germany has given up its monetary sovereignty and is ultimately at the mercy of the money issuing euro banking system.
The US government abdicated its constitutional responsibility to issue the nation's money with the 1913 Federal Reserve Act that transferred US dollar money issuing authority to the private banking cartel. But Congress retains the power to change US banking legislation as needed, and the government possesses other money issuing powers, so the US remains at least legally a monetarily sovereign nation even though the government has yet to exercise its money issuing power. Lincoln issued government money (United States Treasury Notes, "greenbacks") to pay for the North's waging of the Civil War (the South issued their own graybacks), but Lincoln was shot and his greenbacks (and the South's graybacks, which became worthless when the South lost) were taken out of circulation and the "gold-backed" bankers regained control of US$ money issuance.
The Biblical Book of Revelation describes "Babylon the Great", which is a totally corrupt system luxuriating in extracted wealth and power and commodification of human beings like the globalized plutocratic empire of billionaires we see today. Pettigrew was already calling America's system a plutocracy over 100 years ago, as he was losing his Senatorial battles against America's corporate-serving policies of empire building contrary to the spirit and the law of the American constitution. In Revelation, Babylon and all who live in her system fall violently in a very short timeframe. The advice given in Revelation is, "Come out of her my people, so that you do not share in her sins, so that you will not share in any of her plagues".
I think that's good advice, because I don't think anyone can succeed in wresting control of this system from its current rulers, nor do I think anyone should try. In "Plutocrats", Chrystia Freeland quotes robber baron Andrew Carnegie, and members of the new crop of billionaires, expressing their belief that they are "earning" their extreme wealth. In fact they are "extracting" it, as all great personal wealth cannot be earned by individual effort but must be extracted from the efforts of many other contributors. Bill Gates and Mark Zuckerberg, two of the modern billionaires, did not "personally" contrive to extract their billions from the world. Their lawyers and investment bankers and lobbyists handled that bit of the business. Today's great wealth is "corporate" wealth, after all, and a corporation is a collective effort of thousands of managers and employees and contractors working in common cause to enrich their corporation and themselves. Adam Smith described this in 1776, and corporate motives haven't changed in the interim.
As long as the system of mass society provides opportunity to amass corporate scale wealth and power, self-serving people will just keep seizing control of the system's levers of power. So I say the best bet for anti-corporatists is to simply fade out of their mass system and work towards building small scale local solutions. Almost everybody in the world today except peasant farmers depends on the corporate production and transportation system for their necessities of life like food and electricity and heating fuels. If that system crashes, then we lack the means to survive, especially if the system goes down in winter. The grocery stores would be emptied on day one and with no fresh deliveries people would soon starve and civil order would break down. Once we finish starving to death and slaughtering each other "the meek" peasant farmers who never got rich from Babylon and who don't depend on her could very well "inherit the Earth".
So if the question is, "What would life be like without billionaires?" my answer is that it would be a reversion to more simple small scale society where there is little if any excess wealth to extract. I don't think you can defeat the plutocrats and "redistribute" the fruits of corporate production by changing tax policy, because the plutocrats "are" the administrative top level of "government" and they're not going to willingly give up their privileges. I think you have to abandon them and their system and make your own life outside their corporatized power structures.
It is not hypocrisy to use what you need from the system, as it has pretty much already claimed ownership of all the economic resources that we need to survive, and you have already contributed to building up the world as it is. And you don't have to drop out entirely. Just start retaking responsibility for your own and your family's and your community's well being. You don't have to wait for "the government" to solve your problems for you by fixing "the system". The system will probably not get fixed, not in the ways that would benefit you.
Small towns and rural areas are probably better than big cities for more independent living, but even transition towns within big city borders can function as "local" communities that generate some of their own solar or wind electricity, grow their own food and otherwise insulate themselves against failure of "the system". At least some degree of self-sufficiency in providing the necessities of life for yourself, within a small community of like minded people, is a personal security issue. Who knows, it might even be a more rewarding way of life than spending all your working hours chasing the almighty buck.