SAHM here, gave up work 3yrs ago when dc2 arrived, as we can afford it and it's the right thing for us and our family.
I've worked since I was 14, always had at least one job on the go. Guess I fall into that category of "leaving myself vulnerable" as rely solely on dh. It's taken me all this time to get used to it, and I do miss work massively (not my last job, that was Shite).
However, I've been reminded by various friends that you can't go back in time, and as we're having no more children, I'm trying to make the most of my time out of paid employment and enjoy the kids whilst they're young. I've never had a career as such, just jobs, and I'll go back (p/t) when youngest starts school.
I always think being a SAHM is like any other "job" ; you have good days/weeks and bad. I volunteer at a couple of different places which helps keep me sane. I guess if we ever won the lottery I'd do that (and spend more time at the gym/hire a chef/holiday more etc).