I know a bunch of people at Google who started programming in college. I also knew a few people in college who started there and are now getting CS Ph.Ds.

Curiously, it seems to be mostly women who are good devs and yet didn't start until college. I'm not really sure what to make of that. Could be selection bias - since boys are encouraged to play with computers, most of the ones who will be any good at it started in grade school, while since girls have no such encouragement, even ones that are good at it may never have discovered that until college. Or it could be that all boys who are good at computers let it take over their life, and girls have many competing interests. Or it could that only girls have the discipline to become good at something without it becoming their life.

I'm jealous of anyone who can just "come home from work" and turn off their brain about coding and do it as a regular job.

I'm constantly thinking of better ways to do something and find myself rewriting code from years ago. I have at least one "regular job" experience that taught me such behavior/attitude doesn't work well in a 9-5 business environment.

Do you really want to not care about the work you do? It's nice to be able to come home from work and not worry about work, but I wouldn't want to work on something that I wasn't interested in.

Dunno about the OP, but I'm worried about burnout. The road to being "world class" anything is longer than you can imagine, and it'd suck to get 10 years in and suddenly reach the point where I can't do this any more, no matter how much I used to like it, right when I would otherwise be a big success.

It is apparently possible to care about your work and yet still leave it at work - I know a few people that have managed it. I haven't had a whole lot of success myself.