It comes down to bankroll protection.

With midrange professional players, I don't think you really see those kinds of crazy swings. Once you reach a certain level, you start doing dumb things, like playing head-to-head games at ridiculous stakes against players you're equally matched with.

Which is why poker doesn't scale well. Eventually you're not going to hit a level where you don't have as clear an advantage over your opponents. Your profits will eventually end up capping out. You either need to find a new angle or start gambling like a degenerate to further advance.

Players like Matusow aren't going to scale down their stakes when their bankroll starts to shrink dramatically.