This is an oversimplification of the issue with laissez-faire libertarian style economics.
If dollars were the sole driver of markets and was used to keep companies in check, we wouldn't have any need for anti-trust laws and child labor laws. If you want to see a completely unregulated free market like Ron Paul preaches, look at late 19th century and early 20th century US and Great Britain. Would the average worker in these societies say the working conditions and life was great? Charles dikkens would have been out of a job.
People who believe government have a role don't believe simply being rich is a sin in itself. This is a misrepresentation of the stance of people like Bernie Sanders. The issue is the inequality that exists is not simply because there always needs to be a class of poor and rich, but because there is a concerted effort minimize the wealth of lower classes and consolidate the wealth of upper classes. Its intentional and its malicious. Corporations are fueled by the bottom line which is just a euphemism for greed. If that means at the expense of a worker, and they are no regulated to do otherwise, they will put the burden on the worker in order to drive up profits. If companies weren't regulated to pay you overtime, they wouldn't for example.
Lets start to combine this with real social issues that exist and have existed in our society. Whenever a libertarian is confronted with the issue of minorities being vulnerable to an unfettered majority, they have a predictable and untested response. If you mention that in a society like ours, where a white majority sought to oppress a black majority, that under a completely free market system, whites would not see any consequence in using their numbers to oppress a black minority economically. If a white establishment or bank decides it doesn't want to serve blacks, libertarians would argue the loss of income and maybe a business that would do that would drive them out of business. Yet we had more than a century where this did not happen simply because the larger segment of society would be enough to keep these businesses afloat and the smaller population of a minority will have no tangible effect on a business whether they gave them their dollars or not. This lack of power of the minority will always put them at the mercy of the majority. Government in this case through laws and enforcement of the laws can be an equalizer on the part of the minority. Such as the case with civil rights laws and enforcement.
"If men were angels, government wouldn't be necessary" - Hamilton. Sadly this is true. Most of your fellow human beings, if they are not outright pricks, are amoral at the very least.
Libertarian ideals are based on the idea that people are always rational and self-interested actors. However, our politics should show you that a large segment of the population would cut off their own nose to spite their face.Sometimes ideological zealots ignore the power of the almighty dollar to enforce and institute their prejudices. This would be rampant in a libertarian society.