Where Does Most of the Money Come From?

So what hands are the most profitable for everyone? I'm asking because I'm assuming in low stakes you make most of your money from AA-KK and sets. Does it stay this way as you move up? It seems like as you move up, better players won't be paying your sets or overpairs off anywhere near the rate that the lower stakes players do. Am I assuming right? If so, then how do players in higher stakes make most of their money?

My guess is that as you play tighter opponents they will be less inclined to pay off with relativly weak hands (like TPTK). You start pushing them around with weaker hands until they decide to play back at you with a hand like TPTK. Hopefully this is the time when you actually have AA/KK or a set. It will still be the big hands you make the most money on but you probably need to work harder to get people to pay them off.