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.
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Simulation for BTC1 bet:
EV = (83% x -BTC1) + (17% x BTC11) = +BTC1.04
Edit: calculation corrected, credit to Saint-loup
None will say no to this if that's from a legit casino. I would be willing to put 1/10 of my funds or maybe even more if it were possible to do so. I believe if you take into account the win rate and the amount you can earn from it over your winning rate, you'll be able to understand why the computation is very much attractive to anyone willing to take that wager. There is no doubt that this can be a very generous offer on the part of the casino.