This is a perfect example that shows that martingale is not a winning system and if luck turns the other way, you can lose so much more than you tried to win in the first place (the 100 usd was his payout).
To answer the question of how much you can lose with gambling? It's simple, you can lose it all.
Depends on how you are emotionally and how disciplined you are though. If you can stick to strategy, you will never lose more than you planned beforehand.