A lot of expensive hobbies don't have to be expensive. I'm a musician, and I have spent thousands of dollars on musical equipment but realistically, if I weren't going to play out, or record high quality songs, you can get away with just a $200-$300 guitar (you might even be able to go lower. Cheap guitars are crazy good these days), a used amp, a tuner, and a cable. With that alone you have a lifetime of entertainment and challange, and the most expensive long-term cost is your strings. It's honestly a steal in term of cost to entertainment ratio.

Now. That said. The real challenge is not falling into GAS (Gear Aquisition Syndrome), which is a real challange. And if you become even mildly capable on guitar you're probably gonna wanna play live and record too, so, easier said than done, but it doesn't have to be expensive.

Me with 30+ Libreboot desktops/laptops.

my current hobby has so far cost me about $5k over 10 years

We are not a waste of money!

~~hobby~~ family

Gunpla gives me great joy, until I look at my bank account.

Me who enjoys reselling as a hobby.

I do some cross stitching and it hasn't been bad. Even using kits instead of doing custom ones. I've got like $120 CAD worth of large kits and, at the rate I'm going, they'll probably last me a decade or maybe my daughter will inherit some of them.

I'm well into year 2 of working on the current one.