He may be brilliant but he is also a socially challenged self loathing individual or maybe so self righteous he cannot damage his rep by spending a dollar.
Obviously you're the one being challanged talking about dollars on a bitcoin forum.
Bitcoin is not about making dollars dude. You will loose if you keep that mindset
So he hasn't cashed in at all because he believes in his life time the fiat will crash and burn and bitcoin will rise to take it's place and he will be the saviour of the world financial institution.
Like I said...nutty.
Not knocking bitcoin or the idea behind such a currency but can we be realistic for a moment. I can agree that paper money is essentially worthless in terms of backing but at the moment it makes the world go round, thinking you have the best alternative is not the only reason to not cash in a little bit in the process.
After all, there is not a lot he could do with btc to enjoy his life that he could with fiat, just a fact at this moment in time.
He seems to be a very very smart person, so why not. But apart from the conspiracy theories, I guess Satoshi just wanted to make sure people know he isn't Dorian. 
