I'm an avid scuba diver. Ever the domain of the wealthy, scuba diving required both access to the ocean and a shite ton of money for travel & equipment. Not really having any of it, this awesome hobby just kinda passed me by.
The Boeing Flying Fortress. The young men were given 300 hours of intensive training before being deployed to action. The initial rejection rate of applicants was Less than perfect eyesight was a major cause of rejection.