No theory of markets says that in the long term "profits" in general go to zero. Just profits in competitive industries. E.g. steel used to be very profitable. Not so much now. PCs used to be very profitable. Now profits in the PC industry are nominal. But there are always new industries that haven't hit that equilibrium yet.
Seems like this has been trending since at least the 80's.
How long does/should the wave of large profits last until we recognize it as a symptom of a problem?