Why do the guys I give attention to only give attention to everyone else

I have a habit of developing crushes on guys that I show a genuine interest in but they don't bother with me back beyond basic politeness. Yet with everyone else they will be performative, charming, larger than life, never run out of questions to ask and constantly joke around. They are like this with literally everyone else they come across, even people that don't really care about them.

The only difference between the other people my crushes are around and me is that they are more outgoing and socially dominant/popular and I am more reserved. But I'm still cheerful and talk a lot to my crushes and give them plenty of opportunity to be enthusiastic with me too.

Why are guys like this with me but they try harder with literally everyone else? They don't dislike me as I'm nice to them and to everyone else and I never talk badly about others. And my crushes are nice to me, just never on the same level as they are with everyone else.