They can be valuable to the end user, but if the core business changes, implements your wrapper itself, or otherwise doesn't like your wrapper business, you're

They can be valuable to the end user, but if the core business changes, implements your wrapper itself, or otherwise doesn't like your wrapper business, you're toast. And that's why I won't build wrapper businesses. It could be all gone in a week, outside your control. It's happened to plenty of businesses that have made os-level utilities that sit on top of iOS, for example.