Bandwagon Friend
A person or "friend" who only hangs out/ talks to you because you have recently become popular, important or now have something to offer them. They will immediately drop you as soon as you are no longer useful or interesting.
-Now that I've won the lottery I've recently aquired many new friends.
-Sounds like you have a lot of bandwagon friends.
-Sounds like you have a lot of bandwagon friends.