Correct me if I'm wrong Luc, but I think I can answer this because you've covered it elsewhere:

If you watch his videos you'll see he mostly trades against BTC. He's also commented in another thread that he holds "cash" in USDT (tether). I'd be curious for more information on how he manages this too, though.

He's also said that he has never taken a withdrawal from his crypto accounts - he just builds them up. That implies he covers his living expenses through his stock market trading, and all his trading in the crypto markets is just to build up his BTC / USDT.