You walk into a casino, and you play roulette.
You bet
$10 on black,
lose
$30 on black
lose
$90 on black
lose
eventually
black comes out and you win.
I think the only thing stopping you would be the table limits?
Table limites and your bankroll limit that I'm sure it's not infinity. It's a risky Martingale system, x3 on losses. You never know if the next bet will give you the profit to start again, it's like the online gambling, the house always have some advantage and in this case besides the table limits they have one green house, the zero, their house edge.
Yes, that is correct. If winning is so simple than by now, we should have seen many millionaires from gambling and most of the gambling houses under loss or closing the site. But we see many losses in gambling that means all these methods will never work in the longer run. Even with a huge bankroll, people tend to make a mistake of going with bigger bets then lose all the bankrolls. Always gamble only for fun and not earn money from it.