When I was SCUBA training, my instructor made a point of telling everyone in the class :

"There are OLD divers and there are BOLD divers, but there are very few OLD, BOLD divers."

Every single time I had an issue under water, it was when I was trying something BOLD and it brought back the instructors words.

Martyn Farr's book [mentioned in other comments] is littered with examples of BOLD divers but when you look up to see what they're doing now, many of them are dead. Normally related to a cave incident.