That is, when your financial muscle is greater than a casino's and the casino doesn't have a limit on max bet that you can wager. But it is still rather a theoretical case because you just won't be able to bet when the stake becomes greater than the casino's bankroll. So even in this case you are set to lose in practice. Obviously, real-life casinos have max bet limits set in place, for example, FreeBitco.in has it at 20 BTC
Even in that case, it throws up another question you have to answer before doing it. Fiat casinos tend to have a smaller difference between the minimum and maximum bets (or table limits in bricks and mortar casinos). That severely limits the possibilities to martingale to a small number of consecutive losses. When people come to crypto casinos and see min bet of 1 sat and max win of 20 BTC they think they will have to be very unlucky to lose. But the real question is do you really want to risk 20 BTC to win one Satoshi at a time? It could happen the very first series of bets you try it. What Martingale does allow you to do is bet at lower odds than the minimum multiplier. With the right bankroll and base bet, you can bet on outcomes that have much less chance of busting than a 1.01x bet.
Exactly, I've seen this pointed out in other threads where people share min and max bet tables. This is also visible online even in digital fiat casinos, where you even have low-stakes, medium stakes and high stakes tables... All these tables, you will notice, the time it takes for the min bet to reach max bet on simple 2x martingale is very very seldom more than 10-streaks.
Roulette is probably the easiest demo of this, you want to bet a simple 50% chance to win, min bet is usually 1 and max bet is 500. You can't even reach 10-streaks which needs 512.