Having a big pocket pair does not mean, you are supposed to win every single time. Preflop you typically always raise for value with QQ-AA. Its important to not go to small, because you also want to thin the field and get some protection for your hand. If you take QQ 4-ways to a flop, you will typically only have something like 35%
equity, so almost 2 out of 3 times you are going to lose. KK and AA fares better, but even AA will typically only have around 60% equity against 3 opponents.
Postflop a big pocket pair is just like any other hand, and there is no special formula for playing it. It all depend on the board texture, stack sizes, action and the number of opponents. KK on KT5 rainbow is the nuts, but AA on QQ7 or QQ on A74 can easily be beat, and you should typically not put a ton of chips in the pot. In the latter two situations your hand was great preflop, but now many other hands have moved ahead of it, and you need to adjust accordingly.
Even an overpair is not always an automatic stackoff, if stacks are deep. There are certainly spots, where its appropriate to fold AA or KK on a board like QJ825, if for instance the opponent call flop, check-raise turn and jam river. These are just some examples, which I hope can help. The main thing is to understand, you are not mathematically supposed to always win with QQ-AA and get rid of that feeling of entitlement
