The way gambling works is that those offering the games don't pay out fair odds when you win. This is called a house edge and no betting strategies can beat it. So yes, you will fail.
Not true, martingale can work very well in theory, if you have almost unlimited amounts of money, this way the changes of losing are ludicrously low.
This is quite an interesting point, there's a Gambler's Ruin theorem, which says that whoever has bigger bankroll is more likely to win, so if you have much more money than casino, you could theoretically win all their bankroll. Sounds good, right? Well, casino operators are not stupid, they understand that high bets can be dangerous to them, so they always set a limit for a maximum win per 1 bet, usually it's 1-2% of the bankroll. So martingale can't work, because you can't increase your bets indefinitely, and at some point you will not be allowed to double your bet to recover from a loss.