I was curious about it once when I was considering “hustles”. One of the biggest issues may be finding a high-traffic location where you are allowed to operate a vending machine. But if a place could use one and will let you operate for cheap/free, you could give it a shot. One learns a lot from trying. Odds are the work & issues may make it tougher than it seems on the surface (may not be as passive as you think).
This is a good way to find other communities. I sometimes have issues adding communities from other instances. Some of the kinks in apps and lemmy / fediverse stuff itself I’m sure are still being worked out.