I'm 36 now, and with a very comfortable career (12 years) and supporting a family. I'm giving up an $80K salary for start law school in 2005, and will graduate when I'm close to 41.
But I'm a little different than most in that I didn't start my undergrad until I was 33. After HS I did nothing substantial for 5 years (waiter & bartender), but at age 21 I started a career in the commercial insurance industry that I've been in for 12 full-time years.
It was finally going to college (FT while working FT) that changed my life drastically. When I first got the sense that I could go to a good law school and succeed at it, everything just snowballed from there.
The decision to change careers is never easy, and to go down this path is daunting, yes, but it is going to be rewarded big time for all of us - and not just because of the $$.
Not to discount the experiences of those still in their early 20s, but however tremendous this accomplishment is for them, it is even moreso for us in our 30s and up.