I make above $100K working 8x5x48. Been doing it since I was 40. Last two nights I worked 10 hours, but it really was needed. Rarely get called.
I'm smart, but not an expert in anything. I am a damn good trouble shooter and work on old software because new developers are too full of themselves to do it and I have a lot of experience working on code I know nothing about without finding excuses.
My salary gives me a very comfortable lifestyle. I drive a 2001 Blazer because I'm too cheap to trade in a truck that works. A truck I paid $12K for in 2003. I have a 1984 and 1989 Goldwing in the garage that get ridden over 15K miles a year because I see no reason to buy a new bike when I can get a used bike has less than 50K miles on it for $5K and will probably run over 200K miles instead buying an overpriced new bike because "it's cool". I have no debt except for the house, and pretty darn good 401K and savings accounts.
It's amazing how far a good $100K salary can go if you spend it on stuff you need instead of stuff you just want. I do buy things from time to time that I just 'want', I don't live like a pauper. But I've found that a $1000 audio system meets my needs, and 42" TV is actually big enough. So my wife and I spend our spare money enjoying life by traveling a few times a year on long weekend trips instead of stuff that just takes up space.
I have nothing against an extravagant lifestyle. If I could make $200K or more a year doing what I do now with the same level of stress, of course I'd do it. And I'd probably have a newer car and, nicer house. But not the bikes, I live my old Wings.
But I don't think I'm good enough make that much, and I don't think too many jobs like that exist. And I'm not willing to work harder to make it that far.
So I guess self-motivation is probably also a factor.....