As a side note, cars have pretty strict safety regulations, along with a whole set of laws and regulations governing their use.
And still tens of thousands of people die in them each year. I've road raced both cars and motorcycles and my friends thought I was crazy. Always thought (and I'm sure statistics would prove it to be true) that the most dangerous part of a race weekend was the drive to the track.
I'm with this guy, just stay in bed if you want lower risk in your life. Like with Alex Honnold, it's certainly not something I would do, but respect their decision.
And really, have none of us stood above our waists in a sketchy river with no PFD?