You specifically state that you will roll a number 1 - 20,000.
You're the saying the multiplier on a roll under 10,000 is 3.2x. Therefor you have a 50% chance of winning (You also stated this as 51% odd's - It's 50%) 3x your money?
You might want to recalculate...
Read again, it clearly says 21,000!
Also, the percentage adjusts itself based on dice rolls.
I coulda sworn it was 20,000...
And that makes no difference. a 10/21 chance of winning with a 3.2x multiplier is still a MASSIVE negative EV.
Your lucky someone isn't taking advantage of you right now. Then again this could be a ploy to make people think its their odd's for you to more or less take their money
But yeh, definitely look at fixing this. If you're unsure of the formula needed to calculate the corresponding payout & win chance PM me and I'll help you out.