My games make between $2 (for an older machine at a bad location) to $30 (the hottest new pin at my best location...but this only lasts a few weeks) per day, per pin, before split. Average for best location is $10/pin/day. Average for a bad location is $3/pin/day.
I've never operated a one machine public location before, but I think others are spot on that it isn't going to last long before you need to rotate games. I had a single pin in an office, and in less than a month they were already requesting a second machine.
So, as stated above, I don't think you can get away with just operating one machine. You'll quickly need to buy another, and then another, and another. For me, my operating "business" was getting personal loans from me for years, and the business bank account was between zero and $5k the entire time. Of course I kept buying new machines when I got near $5k.
I finally had it all paid back and money in the bank after about 5 years. The only reason this happened is because I stopped expanding (having 27 pins on location at the peak), got rid of my two worst locations, and sold some machines. Had I not done that, I would still have nothing in the bank.
Of course, I did build up a huge amount of games that got paid for one quarter at a time. And if I don't expand anymore, I'll have some steady money coming in because I'll actually be selling old games when new ones come in (since I don't have spots to put them).
I know most of the operators in the area and they don't seem to experience any of the "worst case scenario" situations mentioned in this thread. Sure, anything can happen. It's extremely rare from what I can tell. I'm in a nice area though, so YMMV.
Perhaps as you're alluding to in your last post, from what I can tell, pinball is literally the worst ROI of any coin op machine. I had two pool tables at a location. I bought them retail, for $1200 each delivered, required almost zero maintenance (and actually the brewery could fix most things on their own, which wasn't the case for pinball) and they each made about the same money as a $5k pinball machine. Most pool tables I know of do way better than that.
There is a pair of skee ball machines at a location of mine that make about the same money as 8-10 pins. I've consistently heard of Pac-Man Battle Royale machines making 3x-5x more than a pinball machine.
Pinball machines are some of the most expensive, and most maintenance heavy coin op devices that exist. You should operate them because: it will help pay for your hobby, you love pinball, and you get satisfaction out of providing good playing machines for people to play (who might otherwise not have the opportunity).
All of the large route operators I know of only have a handful of pinball machines, if any. 80-90% of their equipment is other stuff (pool, jukeboxes, crane machines, coin pushers, video games, skeeball, etc). That should tell you something. Kiddie casinos don't have any pins.
The majority of the best playing pinball machines in the country are run by hobby operators: people who have a small number of pins and a small number of locations (or locations that were built by someone who is a pinhead and operates their own machines). It's fun, and rewarding, but if it were super profitable, you would see large pinball route operators springing up everywhere.
The best case scenario is that you have a few pins in your collection already and you try it out by putting one or two out and rotating them with what you have. If you start from scratch and buy a single NIB to try and make money, you're likely going to be disappointed.
However, it is a very low risk thing to try anyway...you'll be able to sell a routed NIB game for $500 or so less than you paid for it. It's just that the ceiling for how profitable it could be to be an operator who only owns one game is quite low. (But you don't have to have a grand plan from the start. I didn't. Just rented one game to an office for a friend. Then they wanted another. Then they referred me to another office. Etc. I wouldn't have been able to do it if I didn't have money in the bank to stay ahead with buying new games before the previous ones were paid off).