Except that it doesn't quite work this way. You are picturing a single four year investment of your human capital but it's more like a leaky boat -- you'll be investing in human capital for far more than four years. So in actuality, you'll study your a$$ off four years so you can gain entry to a residency, where you work even harder for 3-7 years so you can become a boarded physician so you can get a job where you also have to shine or eventually they'll find someone else. You never get to say "I've arrived" and relax -- there's always more running ahead if you want any semblance of security. A lot of us are working harder as attendings than we did in med school or residency because, frankly, while there are plenty of crappy jobs out there we could probably find to pay the bills, particularly if geography was no object, the good jobs require you to constantly demonstrate that you are indispensable. Lots of people would love my job but they won't get a shot at it unless I falter. So It's a race and if you are smart you'll keep running. And that, is pretty much the opposite of a guaranty in my book. And not that different than my life in BigLaw, actually.
Yeah you'll find "a" job but nobody goes through 4 years of med school and 3-7 years of residency to settle into a crappy job with an awful call schedule and below market salary in some undesirable geographic location, where you have no real future. So you'll take something more palatable and need to eternally keep running, making yourself indispensable, to keep it. And in that setting nothing is really "guaranteed." So I'd give this notion of guaranty and job security a rest. It's better than some fields and the floor is a lot higher, but not different enough to base your career decisions.
