It's the same with vulnerabilities in slot machines. Damn rare but they exist - in 2014, when I worked in that industry, one gang made a big bang: in a single night, casinos across Germany had to say goodbye to probably 10 million € [1]. Of course, that vulnerability made massive waves... but from what I heard back then, it had been circulating for many months beforehand. Of course, 10 million € is nothing to sneeze at, but keeping a low profile could have made everyone in the know far more profit.
[1] https://www.t-online.de/digital/aktuelles/id_68982394/softwa...