Since both the player and the casino can’t be the winners at the same time, the casino can’t afford to have long term winning players making bets on the casino.
That’s why in the ToS they usually ban arbitrage/EV betting.
It is simply not good for business (from the casino's perspective). There is a difference between not being good for business (therefore not allowed) and trying to rob a player's winning, which OP does not seem to understand. I have a direct question for OP: would he accept a bet knowing that he will lose for sure? Or will he do any business where losses are inevitable? We all know the answer, so why expect the same thing from others?
If you can’t handle this, don’t play.
Exactly.