Greed. A sane person will walk away from working once they have enough saved to comfortably retire.
$100 million can let you live comfortably forever, but there are plenty of people who want that much every year.
Those are the folks who become ‘leaders.’
[off topic]
I like to read old science fiction and check out the things the authors got wrong.
Maybe my favorite is the ‘mini VHS recorders’ from Neuromancer.