Whats a hobby/craft that you wouldn't expect that has an incredibly high ceiling either monetarily or in sheer skill?
For example, I'm sure the average joe doesn't know just how expensive calligraphy pens can be, or how deep the rabbit hole goes on video game speedruns.
Seen a couple basement setups in my time though tbh never saw an especially impressive one. Most tend to just emulate rural routes and small towns. Always thought more fanastic scenery (Surely there has to be at least one person out there who does D&D figure stuff and trains.) would be great, but I suppose that it would detract from the star of the show.