The obstetrician that delivered my first child used to be an accountant; he wore rubber boots to every appointment and had very entertaining and fluffy eyebrows; He entered medical school at 45; He'll work until the day he keels over but now he really loves what he does where as bean counting was nice it wasn't his true calling. The average career change for each person in the workforce these days is somewhere between 3 and 5 and there is now so much overlap with technology that what you do today may not be what you do 10 years from now. PhD's open doors to opportunities but experience and contacts determine the rest; it's like the old saying. A good Lawyer knows the Law; a Great Lawyer knows the Judge. MS degrees are kind of a stepping stone to either a PhD or a new career path. There are also MPhill's, DPhills and Taught Doctorates (Directors of Operations often have them). That bieng said Stanford and Coursearea have free stuff; no really Machine leanring courses are free.