What's wrong with capitalism? The same thing that led to the downfall of small-c communism: greed. In fact, greed is the downfall of just about every economic system so far envisioned.
Greed is what makes communism fail; if just one person covets more than he needs, the entire system falls apart. Greed is also the corrosive exterior of capitalism, and why regulation is necessary; without adequate regulation, greedy capitalists do whatever they can to exploit the system to get more for themselves.
Because of that very human failing, neither economic system is perfect, but at least regulated capitalism is known to work okay. Unregulated capitalism, however, is a bitch to deal with -- as we continue to recognize. (You'd think we'd remember and learn from our mistakes, wouldn't you?)
So I'm not a communist, in spite of what some of my friends on the right might think. I'm also not blindly capitalistic. To combat unmitigated greed and all the damage it can do, we need regulated capitalism. Proper regulations don't inhibit, they protect -- and everyone, at one time or another, needs that protection.