Completely plausible. I did it at age 29. Worked out great!
In my case, though, I'd have to start from scratch. Like I was 18, not like I was 22.
So it's a really scary idea.
On the other hand, if nothing else changes in my life, I don't want to work this kind of job until I'm sixty-five or seventy. And though it could take at least half a decade to switch, that still leaves me with a lot of years left before retirement. Just seems like I'm still too old for that kind of commitment to change, though.
I guess I'm havin' a mid-life crisis of sorts. ;-)