What's interesting about this study is that they non-scientifically conclude that 'control' is the reason more powerful people are less stressed.

But the reality is, most powerful people do not have 'control' over much.

CEO's who were not founders have very little control.

The 'general' layer in the Army, my god man, it's extremely political.

The reason I suggest is a degree of psychopathy: they just don't care. They accept their status, look upon other people as ants, and are mostly concerned with gaining favour from people at their level or higher.

Secondarily, it could be because they are mostly financially secure - unless something drastic happens, they won't have to worry.

Earning only $500K/year is a different zone than $80K. You can do the golfing, skiing, travel, day spa - i.e. whatever gets you in a happy place. You have the 'second escape home' and can send your kids to college without too much worry.

There's probably multiple factors. My guess is high social status. Having high social status confers a high degree of safety, especially evolutionarily, and yields good reproductive success.