What do you expect to gain in doing this?? They don’t need to be told this, and telling them this is bullying. Are you actually trying to hurt them emotionally?? Because telling them this is just cruel. You’re obviously a lot taller than those you’re telling this to, and telling shorter men/guys that they “won’t have a chance” with the opposite sex all over their height is just despicable
Dude, if some guy tells you that it’s because he is insecure or knows he has no chance and his fragile ego can’t handle you dating her because he thinks he is better than you. He is going to have some self examination to do and he can’t deal with that.
You intimidate him, man.