"If 90% of all players on chess.com are bad players, which seems to be a reasonable guess,"
"Bad" is a subjective description. To say that 90% of all players on chess.com seems very harsh, but it all depends what you are comparing them to.
I like to think that I am not a bad player but I definitely have days when I am.
I think a player constantly trying to improve is good, but I would not say that others are bad for being stuck at an Elo or not playing chess.