To become or not to become a grandmaster

I’ve got two questions on this:

1)      What is the knowledge you need to have to become a grandmaster?

2)      What are the abilities you need to have to become a grandmaster?

Reactions by titleholders are especially appreciated.

Nowadays if you arent a child prodigy and a GM by 10 youll never be more than a ordinary everyday 2500 GM.  Not that thats a bad thing. 

 sounds like any other job to me.

It's less about knowlede and ability and more about the willingness to put in the 10-20 years of constant work.  Ability likely determines whether you become a 2500 versus a 2700 or 2800 GM

Exactly, except that it's not boring, not routine and full of life. I don't know about headaches though.