Usually people do martingale with high odds to keep on roll it until it hits then they stop it. For 2x martingale usually they just using manual betting because it is easier rather than waiting on for examples like 1000 odds or any higher odds. Most of them thought that every martingale will fail but wrong calculation that make it fails so if you can calculate it well and have enough balance I dont think it will fail
Well some part i agree but i think that martingale may not work even if you have big balance .In gambling everything is possible (high loss/high profit).The thing that lies around is the time for how much you put on that strategy.In just a small time it may work but in long time i dont think so that it will work most of the time.You can try it ,for me i already tried it but I tried with lower bankroll but put up a low amt. of bet as well.
If theory you could have infinite winning and infinite loosing stakes. So in the end always winner is the casino.