For a lot of actors, they get into the game for different reasons.
For some, it was about filling that need for attention at any cost. Others, it was a way to deal with internal pain by emoting. Others still just wanted to be famous and acting seemed like the way to do it.
For John Bradley, it was about one thing - meeting Geri Haliwell, known more commonly to the world as Ginger Spice from Spice Girls. In an episode of Wiki How?, Bradley explained how it came about for him - and it's quite pure, to be honest. "Genuinely I said to myself when I was about eight years old, ‘I have to get famous in order to meet Geri Halliwell.’”
As it turns out, going by this episode, Bradley's still a big fan of Spice Girls - and, specifically, Ginger Spice. Take a look.