1) It meets a need (people always need money).
2) It can be run free of your time (you can hire someone you trust to manage the machines for you).
3) You can scale it up (find more locations).
4) You have control.
5) Barrier is so so - you need to do your research for a couple of weeks to find the best location and you need a couple of $5k - $10k to get started.
watch this video:
Idea for a good location; retirement homes ..... old people need money but can find it hard to move around....why not put your machine near their "village" ? Some retirement villages or whatever the correct term is, can consist of hundreds of elderly people.