Preflop play is in many ways rote and simplistic but that does not lower it's importance. It is manifestly true that you lose more money by calling a raise with K10o then by folding a royal flush. What you do when you have a royal flush is extremely unimportant; if you folded a royal flush every single time you got one it would barely affect your bottom line at all.
It's a stupid decision, to be sure, but you get a royal flush so rarely that it simply does not matter. In the case of K10o you are dealt it, or a hand similar to it, several times during a single orbit and that is why playing marginal hands well is a crucial poker skill.
The first thing you must consider in your preflop play is not your cards but rather your position. In a 9 handed table the positions are as follows : The Small Blind and The Big Blind, UTG, UTG+1, UTG+2, MP, The Hi-Jack, The Cut-off and The Button, . Preflop play begins with the player who is UTG (Under The Gun) and post flop play begins with the small blind.
UTG is the worst position and the reason it is poor is because you lack information compared to later positions. The Button, conversely, is the best position because you acquire the most information about your opponent’s actions. If there is a raise, a re-raise and an all in push, Ace King is an easy fold but you don't know this action is coming when you are under the gun.
The next thing you must consider is the texture of the game. If it is loose and passive, that is a lot of limping, calling and small pot building raises but very little re-raising, you can call from early position with speculative hands such as Axs and small pocket pairs. If it is an extremely aggressive game, you will want to fold these

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