If you’d only win the bet by rigging it, you’d already lost it.

A bet is a claim about what will happen, and what makes winning one worth anything is the risk you genuinely took. Arranging the outcome removes the claim: you are no longer right about something, you are just holding the money. Reaching for the fix concedes that your prediction was not good enough, which was the actual question.

Make the bet small enough that you can afford to be wrong, and then be wrong in public when you are. Pay up quickly and say they called it. People will take your side of a wager for years if losing to you is painless.