Boss man could play a game with no house edge and he'd still lose everything. It really doesn't matter if he plays perfect blackjack with barely any house edge or the most rigged keno possible.
The house has an inherent advantage over players in that it has (essentially) infinite funds while you have finite funds. This means that, if you say go on a 5 coin flip win streak and double your money, you are still at risk of losing your entire bankroll if you continue to play. If you go on 5 coin flip loss streak, all your money is now gone and the casino has no risk of losing it back to you. Both these events are equally likely if it's a fair coin flip, but the casino has the advantage even in a fair game because of this. Bossman's strategy is basically to maximise the extent to which this fact fucks him by contiously upping his bet to insane %s of his current bankroll so a mere 5-6 loss streak will bankrupt him, and loss streaks like that are inevitable. Hell, he'd probably still lose it all even if he had the edge.