I started playing it in college, and years later, I still hop back in with my niece and nephew. They're super into creative mode and keep showing me things they built with mods I've never heard of. The game keeps adapting so well, so kids stay interested. And with all the updates and massive online communities, it's not going anywhere soon.
If your son's into other games too, like CS2 or even Rust, and picks up skins along the way, there's this spot where you can instantly sell Steam items for cash. I came across it at https://skinomat.com/ while looking into selling some old CS: GO skins I had lying around. It's not bad if he ever gets into that side of gaming.