Traders selling options need either cash or margin to cover the trade (according to various calculations, not always the whole amount). Their broker also monit

Traders selling options need either cash or margin to cover the trade (according to various calculations, not always the whole amount). Their broker also monitors the risk and will liquidate any position if they feel it's too risky, and they have their own funds and insurance to cover trades. Also the options exchange itself has funds and insurance to guarantee the contracts. There's enough money and liquidity in the overall market that it's extremely unlikely for you to worry about this counterparty risk. It's more of a concern if you're a major investment fund making 9 figure moves and want to make sure banks remain solvent.