...is NOT to impose equality through taxation and wealth redistribution.
It is to prevent the wealthy and the powerful from using their wealth to consolidate and entrench and expand their position so that opportunity is denied to all those who have not already seized it.

Just like businesses, governments don't always work the way they're supposed to, injustices occur and tyranny happens. But the purpose of government, what it should do when properly constituted and executed, is to prevent any one portion of the community from victimizing and exploiting the other. It's purpose is the protection of the individual from violence, and violence is not just limited to foreign enemies, domestic criminals, or government storm troopers; it also includes the manipulation and exploitation of people through economic and "legal" means: financial control of the media, courts, legislatures, markets, employment, labor, goods, services and prices.

Power is power, and those who have it will abuse it in order to keep it. Power in the hands of government is no different, which is why we favor democratic governments than can (hopefully) curb injustices by having the people bring about change through the ballot and seek protection from a constitution. The vote and the law are the instruments we use to prevent the abuses of government power. They don't always work, but they are all we've got. But the power wielded by private individuals or by collectives of private individuals (corporations, companies, etc) has no curb, no natural enemy. Markets do not serve this function, that is how economic rivals compete with each other, not how the community regulates and controls economic power. The market and competition can no more prevent economic injustice than can warfare between criminal gangs restore law and order. And of course, the manipulation and perversion of free markets is exactly how we define business acumen.

Managing a complex society in a chaotic world is not an easy task. It will never be done completely fairly and efficiently, and even under the best of circumstances and intentions it will be a risky business. The vote and the law, balanced against the laws of a free market, are our best strategy for preserving our freedom and our prosperity, but it is not any guarantee we will succeed. But if we let either side of the equation overwhelm the other, either government tyranny or private corporate greed, the fate of the nation will be the same.

It is inevitable that there will be conflict and debate in any free community as competing interests try to hammer out an accomodation. It is not because one side or the other is good or evil, or even right or wrong, they just have different interests; as you point out, "As individuals we should be concerned about ourselves first." But no one group or class should be allowed to determine that their interests are the same as the rest of their society's, and that what is best for them is best for everybody else. Negotiating our way through these great questions is the purpose of democratic government. It should not be decided solely by those who have all the wealth and power. We already know what they want: they want to keep it forever.