Employee retention has been a huge part of my job for over a decade. In the professional world, employees rarely leave over money.
It's generally about opportunities to do new things/grow in their career (which is distinctly different from compensation), a culture problem (which compensation will not fix), or an engagement problem (poor leadership)
The only way I can see what he mean making sense is that he's talking about the people making more than low 6 figures. I can totally see someone making 300k a year not leaving because of money but because they wanna do something new.