This is what being a fan is about!
Not how many years you've been a fan. Not whether or not you were a magazine subscriber. Not how many shows you've been to. Not whether you've met the band or not. All of that stuff is just the window dressing. If U2 is your favourite band, then you are a fan. Simple.
There are no diehard fans, real fans, true fans, casual fans, or so-called fans. Just fans.