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?
That's basically martin gale! If you don't know yet that strategy will never win in the long run.
It can win but you have to have these assumptions to be true:
1. you have unlimited bankroll
2. There is no table limit
Those two are never present, ever! So basically it loses when you,
1. ran out of bankroll because the bet is so big already
2. you reached the table limits