Hypothetical scenario:
You can bet on a single dye roll (choosing a number between 1-6), but if you win you get paid x12 of your stake (instead of x6).
So the Expected Value is positive (see example below), but you'd still have 83% chance of losing.
1 - will you take that bet?
2 - if so, what % of your available funds would you put at stake (i.e. funds you're willing to gamble and afford to lose)?
Again, this is a single, non-repetitive bet.
Even in repetitive betting environment, I tried with martingale but I was unable to finish up my betting profitable. I have experiences of trying with only 10% chances for profits with higher multipliers still nothing worked for me. These all happened only in highly reputed crypto casino but at the end of the day, house was able to beat me.
For a single bet, even if you try with lesser multiplier, I am sure that you will be losing. If you go for martingale (this is not the case here still for discussion purposes I assume multiply betting is allowed) then in short run you may able to recover your losses and if you extend then you may lose all your capital for sure.