The current market is a fine illustration of how markets don’t revert to a mean, and they don’t behave rationally. Pretty much, we can throw those market theories into the toy chest in the attic, along with other diversionary entrapments from our younger days. The theory that markets trend explains the largest set of current phenomena, more than anything else.
To be fair to mean-reversion traders, they don’t presume market returns to be a stationary time series. More often they trade off pairs that preserve statistical canon while individual underlyings behave weirdly on their own. And rational market theorists always, always have an out. It’s almost impossible to refute a rational market theorist because they know all about rationalizing.
It’s still important to understand underlying macro conditions, and in my view it’s important to have a work-in-progress thesis of what’s going on. But don’t let integrity to your thesis prevent you from acting like a drunken bull. Just make sure you get less drunk then everyone else. That may be the only edge you need.