In theory, the PhD is this fantastic credential that opens all kinds of doors. In practice it might make a small difference in your starting salary in industry. The only place where having a PhD is truly important is in a research position, which basically means academia. Even then it is not the last word -- tenure track positions might be out, but there are a number of schools who are willing to hire a good researcher whose highest degree is an MS.
Even with a PhD your prospects may not be all that much better than they are with an MS. I have seen people get a PhD with only one or two published papers, in a field where you need at least ten to even have a serious shot at a tenure track position. If you are the kind of person whose attitude is, "Screw it, I am in school to learn as much as I can and not just to publish a bunch of incremental improvements," you might not even get a shot at an academic job. Sure, someone can pad their CV as a postdoc -- but that is not all that much better than being a grad student, just moderately better pay.
I wasn't talking about PhD as a credential, I was talking about how for the normal good-but-not-Feynman aspiring scientists, going for a PhD is one of the few ways you can properly learn how to do research.
In theory, the PhD is this fantastic credential that opens all kinds of doors. In practice it might make a small difference in your starting salary in industry. The only place where having a PhD is truly important is in a research position, which basically means academia. Even then it is not the last word -- tenure track positions might be out, but there are a number of schools who are willing to hire a good researcher whose highest degree is an MS.
Even with a PhD your prospects may not be all that much better than they are with an MS. I have seen people get a PhD with only one or two published papers, in a field where you need at least ten to even have a serious shot at a tenure track position. If you are the kind of person whose attitude is, "Screw it, I am in school to learn as much as I can and not just to publish a bunch of incremental improvements," you might not even get a shot at an academic job. Sure, someone can pad their CV as a postdoc -- but that is not all that much better than being a grad student, just moderately better pay.