example: if you have friends. actually, you aren't close to them. they are ordinary. actually they don't really need you. and you are a nerd one. but not really nerd. you have a big dream. your dream is to be popular. and one day, you are popular! you are an actress/actor. and unexpected, your friends that don't really need you,suddenly become close to you! and think that you're their best friend.
"why only now they say that, after you're famous! " so, it because you're famous then they want to be your friends! very sly.
there's also same case : they want to be your friends because you're rich! or they want to be your friends because you're beautiful. because you're actor or actress' daughter/sister/son/brother or what ever.
"why not make friends because they feel that you're a good friend and feel comfortable being around you?"