Who Am I?

I could be a serial killer.
But I haven't started yet.

I could be a multi-billionaire.
But I don't have that first billion yet.

I could be a bigamist.
But I'll take it one wife at a time.

I could be a great chef.
But I haven't learnt to cook yet.

I could be a gambler.
But don't bet on it.

I could be a giant.
But that's a tall story.

I could be a loner.
But the voices in my head keep me company.

I could be a poet.
But I have no rhyme nor reason.