If you have 50k budget to bet there is no way you get 20 red in a rows. i think can make bank with this mehtod if you have good budget.
It's surely possible. Even more loses in a row is very likely. You will finally lose. Be sure of that.
Assume that you have 50,000 dollars. You want to double it and the house edge is only 1%.
If you play at 2x multiplier, you have 49.5% chance to double your balance and 50.5% chance to lose your balance.
Now assume that I try to double my 50,000 dollar using martingale strategy.
I set the base amount to only 5 cents. If I lose the bet, I will double the bet amount and if I win the bet, I return the bet amount to 5 cents.
Let's do some calculations and see if my chance increases.
I can continue until I lose 20 bets in a row.
As with every win I win only 0.05 cents, to double my initial balance, I must win 1 million bets.
The chance to lose 20 bets in a row is 0.505^20. That's only 0.000117%. Till now every thing is OK.
To double my balance, I have to win 1 million times.
The chance of not losing 20 times in a row until you win 1 million bets is (1-0.00000117)^1,000,000. That's 31%.
Therefore, the chance to increase your balance with martingale strategy is 31% while the chance to that with a single bet was 49.5%.
This is how martingale strategy decreases the chance of success.