Neither particularly brave nor stupid. People have dived with sharks for ages. It's almost unheard of for a diver to get attacked. When they do, it's usually in an area with a history of cage diving.
Somewhere I have a VHS of a shark swimming directly at me - I didn't really notice how close it was because I was watching through a 20mm lens at the time. When it got very close I breathed in slightly and it swam beneath me between my legs. It was only when I watched the video that I saw how close it was.