Enterpreneurship is much more than just running a startup. You can build a product by bootstrapping it and start selling. You don't need to go all in from the very beginning, but you can build and try selling that. If it ever sticks, then you can go all in.

Also, you don't need to come up with something totally new that has never existed before. You can also build something that is already proven to have use for. Much easier to sell a little better or a little cheaper product to markets that exists instead of trying to create markets for something no-one has ever used before.