The system goes something like this:-
You sign up for accounts on online casinos, and then play roulette using the following strategy:-
- Bet £1 on red (or black - let's arbitrarily say red)
- If you win, pocket the winnings
- If you lose, double your bets (e.g. betting £2, £4, £8 etc) on red
Or not. It doesn't actually work, because there are 3 facts which have been ignored.
The principal one is that the odds of red (or black) coming up are not 50% if there is a zero (or double zero) on the board - actually, it's 48.6% or 47.3% respectively. This means that you should expect to lose each spin of the wheel.
That's OK, you might think, because you can follow the strategy, and still win, because you're bound to win on a subsequent spin. No - two factors limit this: 1) the size of your bankroll; 2) the size of the table's maximum bet. If you don't have the money to bet, you can't continue in the martingale system. If the table won't accept your bet, you can't continue in the system.
Therefore, on average, you will lose, since you will tend to lose on each spin.
Do not believe the hype. If you actually simulate the process, you will find out how often you will win. It's almost as if people who run casinos aren't stupid...
(There is a very good article on this at The Wizard Of Odds)