Martingale System is for veeeery rich person. In this system you will win only on paper.
Nah, most gambling site have max bet so

This is one of the biggest problem of this system.
Next one is that we need a huge bankroll.
Huge bankroll is infinite. You will lose in the long run no matter what. Varience ensures that you don't get the same amount of win and loses, you will eventually hit a very long streak and there goes your bankroll. Also, the house edge decreases your likelyhood of winning.
100% right.
That is way I prefer the d'alembert system. There is less profit but our bankroll is more safe.