[WalterBright]

> then the profits tend to zero

That makes as much sense as people working for nothing. I don't see any explanation for profits tending to zero, either.

I wonder why "perfect" markets are even a thing. It has no applicability to actual markets. It offers no insight on actual markets, and offers no useful predictions about markets. It's about as useful a model as the Monopoly game is - i.e. none.

I've seen many people claim that a "perfect" market is a requirement for free markets to work well. This isn't remotely true. "Perfect" markets and free markets have nothing in common.

"Perfect" markets just seem to be a strawman put forth by people who argue that since "perfect" markets are unachievable, therefore free markets are no good.