How does it feel to lose when you're right?
You called the outcome. But the price dipped on the way, your margin ran out, and the position was closed before the event resolved. Margined products bet on every move along the way. You were betting on the ending.
Pay once. Keep the position.
A call or a put on the probability itself, priced by the users who write and trade it. You pay the premium up front, and that premium is the most you can ever lose. No margin, no maintenance, no forced exit. Whatever the underlying probability does in between, the position stays yours until expiry unless you choose to sell it to another user on the order book, where the option's own price is set by supply and demand.
Users set the price. The market settles it.
Your entry price comes from the resting order book; advisory fair value helps you assess it but is never an offer. At expiry the contract settles in cash against the event market's own price. Finish past your level and the payout is the distance between them. Miss and you lose only the premium.