You ask a good question.
I remember we had a gent, who was a Raytheon VP, join up in the reserves. Had his own airplane. First assignment was Urinalysis Coordinator. He loved it.
Another gent, high time senior captain with an airline, came back in as an O3 and it was even questionable he would get enough good years to retire.
So often I see on LinkedIn the pictures of guys who are in the reserves is of them in uniform. That sort of stuff is hard to categorize in dollars and cents, but means a lot.
I do volunteer EMS, which pays less than zero in money, but helps give a purposeful life. It’s a similar thing for a lot of people, I imagine.