and assume started with 0.00005 BTC (5000 satoshi) with automatic betting , every 1 second 1 bet
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 ~52
BTC 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 can make you have a slight advantage over the others.