Strategy is needed in gambling, but it's not just for pure-luck based game only like martiangel. It also about how to maintain your bankroll (bankroll management) and know when to stop for that day.
The Martingale System is very old invention. At first it seems like it can be helpful but it is just an illusion. The biggest flaw is that The Martingale system does provide a way to eliminate losses, but it requires an unlimited bankroll and a betting site without limits. And it is simply impossible to achieve.
If you want more detailed explanation you can read:
http://www.pokerbankrollblog.com/the-martingale-system-and-why-it-doesnt-work.htm