When you register a domain, you are prompted to put it for sale. You don't have to. As the article points out, a lot of people register domains for optionality.

When you register a domain, you are prompted to put it for sale. You don't have to. As the article points out, a lot of people register domains for optionality. Maybe one day I'll use that for a project. And that optionality isn't worth an infinite amount of money.