No, I really don't think they would. The gym is a lot of people's "third place[0]". Not to mention that exercise in particular releases happy chemicals independent of whether or not it is making/keeping you fit.

0. https://en.wikipedia.org/wiki/Third_place

I think you're missing the point though. These are people who aren't optimizing for quality of life as most people define it (i.e. work as little as possible and reap maximal rewards and time with people you care about). Work / achievement / solving problems / obtaining resources becomes the goal itself. It is never enough because you can always have more / there is always something else to do / there is always another problem to solve / there is always another company to start etc.

Its the same thing for people who are serious about the gym. You can deadlift 600 lbs? Cool, now its time to try to get to 650. If you hit 650 it is time to plan for 700.

I'm a lifetime "fitness person" and I know for myself and quite a few others like me that being fit is a side effect of exercise not the primary goal.

I disagree.

I enjoy the act of exercising and the immediate effects following excercise. Most people that are very into fitness or exercise enjoy it as well.