Well at least as an investor martingalers are great as although they may take money in the short term you can guarantee that one day you'll get their whole stack.
It's looking like that 64 BTC loss was this player's last bet. They've already withdrawn hundreds of BTC of profit over the last few weeks. Maybe they have the discipline required to quit while they're ahead!
he will be back. no doubt about it.
i may try this
I bet that he will be back as well
They were very lucky if they withdrew hundreds of btc from a 0.5-64 martingale