Your view of morality is pretty one-dimensional. Yes, both of you are taking advantage of others. Yes, both of you are trying to win money. But doing it through skill is socially acceptable, while doing it through card mechanics isn't.

There are situations where it might be acceptable cheat - maybe wannabe magicians playing for penny stakes where it's understood that cheating is part of the game.

And there are situations where using your skill to maximize your winnings is unacceptable. In some friendly home games trying too hard to win is frowned upon and would lead to not getting invited back.

I don't think social acceptability should have much to do with morality, do you?

My point is that it does. And I think that's fine too in most cases.