Every option has a seller. Writing an option means being that seller: you receive the premium, and in exchange you take on the obligation. If the buyer uses the option, you face assignment — you must sell the underlying at the strike (for a call) or buy it at the strike (for a put), however far the market has moved.
The premium is the most a writer can make; the loss is set by the market. A covered call is written against shares you already own, so if it's assigned you hand over shares you have — giving up any rise above the strike, while still carrying the full fall if the shares drop. A naked position has nothing behind it. A naked put can cost up to the whole strike price if the share goes to zero. A naked call writer has to buy shares at whatever the market price is in order to deliver them, and because a price can keep rising, that loss has no ceiling.
The writer's gain is capped at the premium. The loss isn't.
Educational content only. It is not personal financial advice.