Martingale works, his bets were just too big for his bankroll. You need to have enough to take 10 losses at least before you win one.
You are half right. He was betting far too big for his bank, so the inevitable big loss came quicker than should have been the case.
Even if he had bet small or had a massive bank, he would lose it all eventually. Martingale is just pushing the losses back, until eventually the odds catch up with you and you lose it all!