Theoretically, if you have an infinitely large bankroll, you will consistently win money in the long run. Of course noone has a bankroll that big,
Infinite bankroll is not a guarantee that you will consistently win in the long run especially if you use martingale. And this has been discussed several times, so you need to check some previous posts about this.
do you mean that if you have for example 1,000,000
BTC (i mil) and started from 0.00000001
BTC (1 satoshi) you could lose at some point ?
p.s. i know the numbers are unreal but we are theory crafting about an infinite bankroll here.
Why not? Bets are independent of each other, that means the chance for you to lose the next bet is always the same no matter what your previous rolls are.
If you agree it is possible to get 20 losses in a row, you have to agree that it is possible to get 21 losses in a row and the chance is just halved, so on and so forth.