Or if you enjoy the process of building it. Or if the process of building it will help you relax or something so that you'll be able to do more things-that-provide-more-value later. Or if you're trying to impress someone. Or any other of the reason people have hobbies.

Those are all reasons to build things. But not the subject of the context.

If you want something to exist, make it!

Closely related principle: Purchase Fuzzies and Utilons Separately.