Why do side hacks made for fun often outlast our heavily planned projects?

There is something strange about how we build things. Whenever I spend weeks sketching out features, setting up fancy task boards, and thinking about growth strategies, the project usually dies within a few months. But when I just spend a Saturday night messing around with a fun code idea without worrying about the final outcome, it somehow finds a real audience.

I think when we stop overthinking and just create things for the pure fun of it, we end up solving real problems more naturally. How do you decide which random side ideas are worth shipping versus the ones you carefully plan on your roadmap?