That's certainly one way to look at it. Another is that people who work on my team build the skills and confidence that enables them to move up in their careers, and at some point they outgrow what I can offer. I'm usually quite happy that they've been able to do that.

If someone has a chance to take another step up in their career that's a good thing. If I offer them more money to stay at the same level they'd be silly to accept that.