Gianni Santino's ATM route was not a retirement plan. He went from the Marines to police work, missed time with his wife and three kids and still felt behind.

A real-estate side try made it worse. Tenants stopped paying and the bills stacked. Then he noticed a beat-up cash machine in a busy spot, charging high fees, with a line of people using it anyway.

He bought his first machine with a few hundred dollars and put it in a local shop. The first transactions felt different from rent that did not arrive. He says the route now runs about $35,000 a month.

One machine in one shop

On Upflip he walks through placing that first ATM and watching the transactions, including machines that also handle crypto-style cash demand he saw at the counter.

The monthly figure is his. The start was a tired machine he did not own yet and a few hundred dollars.