What would you think if I stole my roommate's $10 bill that he threated to burn?
That doesn't sound good. Why are you stealing it?
He claims money means nothing to him, so I want to prove him wrong.
I think you are going about this all wrong. It is wrong to steal from others. It is not really teaching him a lesson and is just making you feel better instead.
I don't care.
Nevertheless, if you want your roommate not to kick you out or get you in trouble, you'll refrain from stealing his money.