The answer to that question has been analyzed in an infinite web sites. However, it should be emphasized that even when the answer is an absolute NO for Martingale in long terms, it is possible to obtain profits in short terms.
To obtain profits by using martingale you should take into account these advises:
Determine your sequence:
There are a lot of martingale sequences you can use. It depends on the bet you are going to place. In roulette, it is not the same martingale sequence for a line bet than for a color bet.
Define your limits:
set the maximum bet you are able to place in the table.
Take your time:
Analyze the roulette behavior to determine when it would be the best time to place a bet. Check the delay of the numbers and take a decision.
The most important:
Once you have won, stop betting. Hit and run is the best strategy when you are using Martingales sequences.
Now pay attention to the basic explanation of why Martingales in long run do not work:
Casinos have the advantage. Remember that the roulette’s payouts are calculated to be lower than they should be. In each roulette spin you have more chances to lose than to win.
Your bankroll is not infinite. Most of the people think that it is impossible to lose 10 bets in a row. However it has been calculated that color bets can have a delay of 13 or 15 roulette games. If you find this kind of losing streak, it is almost impossible to not finish broke.
The table limit. Imagine that you have an infinite bankroll. In that case, casinos never will allow you to double your bet indefinitely. They have limits to avoid that kind of behavior. Which make a martingale system almost useless for high amounts of money.