There is more to poker than just getting KK and stacking off on a J 4 3 2 9 board.
Part of poker is understanding your villains.
Let me give you an example, this happened to me the other day. I was playing 2/5nl, eff stacks $1.2k
I was dealt KK in the CO.
UTG was an aggro spewtard, LP was an aggro spewtard, SB was a very competent and winning TAG. Me and SB have history and he knows I'm a good winning player.
UTG raises $15, LP calls, I 3-bet to $65, SB calls, UTG calls, LP folds. 3-way action.
Flop($210) J 4 7r
SB checks, UTG checks, I bet $150, SB calls, UTG calls.
When SB calls, I think to myself, "crap." But why? I mean, I have KK here and the board is bone dry.
Here is where the other dimensions of poker come to play. SB is a very competent winning TAG and he is NEVER calling my $65 preflop 3-bet with AJ or KJ or QJ. When I raise to $65 my range is TT+, AQ+, KQ with majority of weight being to TT+. Thus, since SB is a competent TAG he is never calling my raise with a reverse implied odds hand like AJ. His 3-bet calling range will be exclusively 22-TT set mining and an occasional JJ/QQ that he will play post flop for value. He may also have AA/KK and the reason he would flat that as well is because he doesn't want to chase out the aggro spewtard. He would/could then check flop since he would know that I'm c-betting near 100% of the time.
So, when he calls my flop bet on this bone dry of a board his range is 44, 77, JJ, QQ, AA (I discount KK since I have KK). Out of his entire range the only hand I beat is QQ
Lastly, SB can also call me here with 88, 99, TT to reevaluate next street since AK is in my range. That is possible and if this is the case I expect him to check/evaluate turn.
Now, the spewtard has a wide range that includes sets but also Jx and even gut shots and/or smaller pockets that put me on AK and think I whiffed. Obviously i'm happy to get it in with the spewtard but I know I'm dead against the SB.
Turn($660) T
SB bets $400, UTG calls, Hero????
When SB leads out he's doing so because he doesn't want to lose value from the spewtard since I would have to check back AK if I whiffed. So when he leads out for a strong bet I know I'm crushed by sets and possibly AA and the only hand in his range I beat is QQ, so I fold my KK
River(1460) J
SB goes all-in for $600-ish, UTG snap calls
SB had 77 for the fullhouse
UTG had KJ for trips
Now, if SB had been an aggro spewtard I doubt I would have been able to get off the hand because his range would have included too many hands I beat. Also, if I were only $300 or $400 deep I probably would not have been able to get off the hand. But because SB was competent and we were both 200bb+ deep I was able to narrow his range and get off the hand...
So my point is that its more than just being dealt cards. You have to have a read on your villains and understanding of their tendencies.
If you are up against villains that will stack off 100bb with TPMK or TPGK then you can never fold your overpair against them.
If you are up against villains that will never stack off 100bb w TPMK or TPGK then you need to seriously consider folding your overpairs to them
If the action has progressed such that your villain's range narrows to monsters then you need to be folding your overpairs.
hope this helps