Of course I may lose everything and not pay you a single dime , its freaking gambling in the end there are no definite ways to beat the house.
This pretty much sums the whole idea up.
In reality, if he wins he'll take a cut and if he loses he technically doesn't lose and you do. Not to mention he could also pretend to have lost and actually won/not gambled which means that you basically gave your coins away for free. If you want to gamble guys, do it yourself.