I think that the main reason they haven't taken off since the beginning is because of the heavy penalties from regulators.
In order to operate an atm requires money business transfer licenses and things of that nature.
At least in the states it does. I think you have to register both with state and federal government but I'm not 100% sure. It's best to check with you're local parliament and financial professionals.
Don't forget also the insurance. Maybe some security to protect it if you want, depends on what your numbers tell.
It is normally a pretty cool business, especially when the price skyrockets. That's definitely and by far the best time to do it. If they wait until then and put it in a really good place then it would be pretty good for them.