DIY projects always get glorified like this. As if people figured out this secret trick to bypass consumer capitalism. When the whole idea of capitalism is about not having to invest a ton of effort into learning a new craft every time we want to use a new product/service. We pay companies to master that craft for us with money we earn from focusing on our own individual skills.

It'd be more accurate to sell it as a rewarding experience to do as a hobby rather than a clever cost-saving commercial solution.

If money and ROI is the primary focus then most specialized knowledge could be better utilized in other ways than simply building a product once for yourself in your spare time.