This is one of those arguments where you need to clearly seperate between the legal and the moral arguments. Profit is the legal money you gain for your efforts, and corruption is the illegal rewards you claim.

But this is independent of the moral arguments. The profits claimed by a large monopoly may or may not be legal, but they are always immoral (by my standards of morality). It's normally not a big sin, though it can be in cases where a company uses a monopoly to charge large sums of money for things necissary for life. There are also cases where you may have moral claim to profits but no legal claim.

Morally speaking, I see no problem with people profiting from their efforts and investments. But this profit must be proportional to the amount invested to be morally sound. However a open market isn't interested in the amount of effort put into something, only in the demand for the results. Thus some items are expensive because the supply is limited and the demand high, even though little real effort is was expended by the seller, while other items sell for a low price despite great effort expended in it's manufacture.

In theory, in an open market this would balance itself out as people would increase the manufacture of expensive items and stop selling cheap items. But the world is not an ideal place and economic theory is highly idealized. There are items that simply can not be produced by just anyone nor can the volume be increased freely. And conversly there there markets that are oversaturated but people continue to enter because that is what they want to do.

The end conclusion is that you can't look to capitalism to answer moral question. It doesn't answer the question of what is right and wrong, it answers the question of what is profitable. In an well balanced open market, this is a good thing usually because the goal of profitablity leads to great efficency, which leads to maximum overall benifts for everybody at minimal cost. But the real world is always less then an ideal free market, and people do have to make moral choices.