- people try to wingsuit through narrow obstacles and miss
- people try to build their own planes and helicopters and die
- people try to build submersible vehicles to go see the titanic and, uh, don't have a 100% success rate
- people try to build steam-powered rockets and die
"It's their life, they won't fuck it up" doesn't exactly cover a lot of behaviors.
I'd argue home-rolling your own medical device firmware is closer to daredevil/"hold my beer" behavior than normal.