Before anyone believe on this story. Who will bet all in on a roulette game at first bet? Of there are some users then they are rare. Some user are doing multiple account and avail promotion such as cashback while betting both side using 2 accounts. This way, the user can claim the cashback while 100% still holds his original bankroll that go to the winning bet account. His only danger on this method is when the ball goes to zero which is very low chance to occur.

A french roulette game gives 50% refund when ball goes to zero. I believe this is what he use.

This kind of bonus abuse is very popular which the live casino provider usually detect multiple account that oppose bet even on 2 different casino involved that play same live game.