Adam Smith himself once pointed out you couldn't put two merchants together in a room without them trying to figure out a way to game the market for their exclusive benefit at the expense of their competition and the customer..

The problem is power. People (or organizations) with power are not going to give it up, whether it be economic or political. However, they're quite capable of working together to come up with a scheme to share it amongst themselves, and keep it out of a third party's hands.

Capitalism is like democracy, it utilizes conflict and competition (the market or the vote) to prevent anyone from acquiring too much power. But in either case, there is no guarantee that equilibrium will automatically lead to justice and prosperity. Capitalism needs regulation or it leads to oligarchy or plutocracy. Regulation must be supplied by the state. And the state must be administered through constitutional and democratic institutions; certainly not commercial lobbying.

Its a three-legged stool.