If you’re taking 25% away from something, then you are always left with 75% of something, so you never reach zero. That is the smartass maths answer.
The maths is fairly easy here, because of the 10% losing rate.
You will have 2 consecutive losers once in a hundred (O.1 squared)
3 consecutive losers once in a thousand (0.1 cubed)
4 consecutive losers once in ten thousand etc
I suppose the thing to do is to set a lower limit such as 1% of your bank, and then work out the probability of that level being reached (within a certain number of bets).
what price would you give me on the 4th one winning? 9/1 or the 100,000/1 (approx) that you reckon it should be. And the more important thing, if your strike rate is 90% then the price you get has to be better, otherwise you’ll loose in the long run.