to lose all he got (and here is 52.4288 for example) , with Martingale technique he got 20 chance to win 50% for each
-snip-
There are few things that is off with your "calculations" that you forgot to take into account :
#1 If you actually has ~52BTC you wouldnt want a dust bet of 5000 satoshis. It is much better to play at a higher base bet and not to
use martingale at all. It is proven many times that martingale could be one of the worst strategy however a variances of it could be
used for better chance to win
#2 Roulette has an edge of ~2.7 % for single zero wheel and ~5.4 for the double zero wheel and if you actually want a 2x payout
martingale then dice would be a better option because of its lower house edge or even BlackJack for the 1% < house edge
#3 The probability to get over 20x loss streak is not actually "rare" is most cases it will happens at 0.00011637 % chance . Number is
actually close to zero however this happens quite a lot
References : http://dicesites.com/tools
Dont spread lies, martingale is not proven to be one of the worst strategies, such thing does not exist, all the strategies are bad, in fact martingale, doing it right can make you have a slight advantage over the others.