He is survived by two kids, and was age 64 anyway.
The vast majority of not very bright people will live into old age. And it doesn't make sense to label as "not very bright" someone who was capable of building and launching rockets big enough to carry a person. The term "rocket scientist" is used to describe highly intelligent people for a reason. Rocketry is dangerous business, no matter how intelligent you are.
Intelligent people don't strap themselves into an unproven rocket built in their backyard shed. Any fool can build a rocket that goes a few hundred or thousand feet, you only need a few seconds of thrust in the right direction.
An intelligent person would look at it and think to themselves "holy crap, there's no way I'm getting in that thing".
Just because someone can do a few calculations and build a rocket, it doesn't mean they are intelligent. My computer can do those calcs too and it's as smart as a house brick.
Intelligent people have the ability to analyse a situation, including those of their own making, and see the problems and dangers that are present, and act sensibly in response to those.
The fact that this guy killed himself in a dodgy rocket which was basically just a big steam pressure tank with a nosecone and seat proves that he didn't have the sense or brainpower to see the dangers. Of course, he may have just been plain nuts, and being a flat earther kind of points in that direction...