[LearnedfromTV]

I think you are right that the multiway pot doesn't happen a lot. But I think it happen more than you think, mainly because:

I think you underestimate the value of playing a three or four way pot with a pocket pair or an ace given that your hand is hidden and KK's isn't and you can bluff. A basic strategy for KK is to payoff all bets, which means hitting a set guarantees you a small bet on the flop and 3 big bets, getting a raise in on the turn or river. Even if KK knows you have an A or a pp, any flop can potentially be one where you outflopped him. If he starts folding to aggression to save bets you can bluff to gain them back (and then some).

The other thing to consider is that if it is a game you can beat for $50/hour, someone in the field isn't playing perfectly. Given the right distribution of hands, one or two bad calls can encourage several correct calls. Even if the first calls is profitable for KK, the sum of the calls probably isn't given how hard it will be for KK to play correctly postflop in a multiway pot.

Also in multiway pots, the bluffs that are run at KK can be two-bet bluffs. Say it is three way: SB has AJ spades, BB has QJ. Flop QT2 two spades. CHeck to KK, KK bets, SB semibluff checkraises, BB three bets. If KK decides he is ahead he still has to dodge sixteen outs, and some percentage of the time he faces these bets SB was bluffing but BB flopped a set.

All of this is just rough musing, but the one thing I'm sure of is that the calculation is made very complicated by the multiway possibility, and it isn't irrelevant.