If that's $600K after taxes, and a year of college for a single child costs $80K at an excellent school, and you've got two or three kids, and housing in a major metropolitan area...
I mean you're definitely living very comfortably, but there are still lots of ways to spend money that have a big impact on your life, between your home and child care and your vacations and your comfort in traveling.
If the number is $25 million, then sure there isn't much more difference. Probably even $5 million. But $1 million still has plenty of room for very meaningful life improvement, that isn't anywhere near private jets. Not that you need, but that it's entirely normal to want.