Poorly defined problems often come down to things like creativity and your ability to handle emotions. Sometimes you have to follow a seemingly senseless curiosity to find the right path forward. Sometimes it is about finding beauty where it isn't expected. Also these problems have multiple valid and fundamentally different solutions and can be highly subjective. Think art.
Well defined problems are about juggling multiple things in your head, high concentration, relying on fundamental knowledge, heuristics etc. All of that possibly under pressure. There might be multiple solutions but they are typically on a scale (good enough vs perfect etc.) or are choices between measurable tradeoffs. Think engineering.
Or it'll be seized and hoarded by corrupt governments or militias.
It seems plausible. For instance, would a good accountant (well defined problems) necessarily make a good physicist (poorly defined problems)?
Seems to indicate that the threshold hypothesis (IQ helps creativity/divergent thinking up to a point, then levels out in correlation) is largely correct
"One way to spot people who are good at solving poorly defined problems is to look for people who feel good about their lives" seems like a circular definition. So people that feel good do so because they are better at solving poorly defined problems? How do we know?