primedice if fair but sometimes i lose 50% chance bets 10 times in a row
This is very usual after a certain amount of bets.
I have already seen several losing streaks which were much longer than 20 in a row.
That is like flipping a coin. If you flipped it thousands of times, there is a good chance that you will see heads or tails come up 10 times in a row.
The exact probability of that happening can be found on google. I don't know the exact equation...
Each flip is independent, 0.5 chance of a partcular outcome. So, your chance of 10 heads (out of 10 exactly flips) = 0.5^10 =approx 0.000976
So, if you flip 1000 times, you have a 90% chance that there's a run of 10 heads in there somewhere. Isn't that corect?