When you bet on martingale, it is normal that you may not realize 19 times in a row win as well. If you bet on 10 satoshi per bet, you are going to win 190 satoshi when you go 19 wins in a row, not really a ton of money right? But, when you lose 19 times in a row and start at 10 satoshi and double it every time you gamble you are going to end up at 5,242,880 satoshi or better yet 0.52420880 bitcoins, that is over half a bitcoin at the last bet and of course a ton more until you reach there, almost one bitcoin lost, and you only try to win 10 satoshi when you recover it all. So, it is understandable that you may not realize 190 satoshi won thanks to 19 wins in a row, but it is also easy to calculate 1 bitcoin loss when you go 19 losses in a row.
No, it is not rare to have 19 times losing streak in a dice, others even goes up more than 30x in a row. And btw 5,242,889 satoshi is just 0.05242889 BTC not half of Bitcoin since 1 BTC is equivalent to 100 million satoshi.
Though martingale is a devastating strategy when a consecutive losing streak happens, but 1 win after long losing streak can easily gain what you lost plus some winnings depending on how much is the multiplier you set up on it.
Why to gamble with bitcoin then? Whole bitcoin is 11k, but if you take $10 you can play with many doge coins, for example, or little less trons or xrp!
I like to play x99, where you can have more than 700 reds! It's not advisable to play that kind of strategies with bitcoins, you need to have whole coins, a lot of them. At x2 I had 30 reds, but as I see people in chat some of them had even more! It's a streak that happens once in tens millions rolls, but that can happen!
For days, I am playing x7, my max red streak is 53, people in chat talks about over 100 reds at x7. It's usually around 20-30, but once in 5k rolls I got over 40 reds. Today after two days I got 53 reds!
Just multiply the multiplier with 10 and you got the red streak which can happen easily. So 20 reds on 2X, 70 reds on 7X and 100 reds on 10X. Bigger numbers are also possible but they are more rare.