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.
"Almost unlimited amounts of money" will still prove it to be a fail. The premise of "not getting fair odds" has not changed. The risk of finding a busting sequence will always be greater than the reward you are targeting in a -EV game.
True, you need "unlimited amount of money" to get a martingale system to work and that is practically impossible for anyone too. Another issue will always be the maximum bet. Regardless if you have unlimited money, you still cannot go over the maximum bet amount. Which means if you have the longest losing streak in history and you have unlimited money, you cannot bet beyond the maximum hence destroying your system.
You can also bet really small. This will cause you to win very little but also increase your margin of error.
If you bet 0.001 only 10 losses in a row will force you to bet over 1BTC and this is stepping into some serious gambling. To be safe you'd need to start much lower, like 0.00001, which after 10 losses in a row would lead to betting 0.01 and another 7 losses to pass 1BTC.
This still doesn't make the method safe! Most people will run out of money after 17 -18 losses in a row.