He has nothing. It's a ponzi scheme, so all funds get paid out as interest payments until he can no longer get new funds and they dry up, ponzi goes bust, he disappears.
You could sue each other to claw back interest payments, since it was probably your money who went to everybody else. There's nothing left to recover. Madoff had nothing to show for his $50+ billion ponzi.
So then who owned the bitcoin address that had 500k coins in it and then started shipping coins off in large chunks to many other addresses after the scheme broke down? Total # of coins exchange could be >>500k with 500 being the peak when all the cash out reqs happened.
More here: https://bitcointalksearch.org/topic/m.1196791