They have to past a special exam that test all sort of skills. Since it's such a good job hundreds of thousands of people take it. Only ten or less pass from what I heard. Recently only one person passed.

[He's smirking slight after that last statement.]

Yeah, my friend Gon is a rash, head-strong idiot. From what I heard about his dad, he gets it from him. I can't help but admire him for it...at times.