Earlier quoted context omitted.
Confirmed, Chicago has multiple billion and hundred-million-dollar businesses built on Ruby on Rails. A lot of it stems from Basecamp being based here, so Chicago had a lot of early adopters. But those early adopters have spawned new companies using the latest versions of Rails decades later.
That may have been intended as hyperbole, but Rails is only 15 years old... https://en.wikipedia.org/wiki/Ruby_on_Rails#History
Yes, slight hyperbole in that it was >10 years off the top of my head. Your statement is correct.