I don't agree with your 50% figure. Symmetrical, sure, but remember the blind bets. Once that money is committed, each player can have a higher EV in playing

I don't agree with your 50% figure. Symmetrical, sure, but remember the blind bets. Once that money is committed, each player can have a higher EV in playing the hand than in folding. (Related thought experiment - consider a game where each player has $101 in front of them before the hand starts, and then post $50 and $100 blinds. 100% of hands should be played from each position.)