The release of the movie The Banker was put on hold by AppleTV due to a scandal but the information in the link provides a bit of insight into what Bernard Garrett did to get his own bank:
https://law.justia.com/cases/federal/appellate-courts/F2/396/489/216152/
This was the trailer:
Interesting.
There were a lot (I mean, A LOT!) of Hollywood movies
'inspired by true events' where the storytelling was not entirely accurate; is the 'The Banker' where the line is drawn?