What do you mean by "career"?
Judging from the job postings I've seen, it may be better to have 15 years of experience than a PhD.
Anyway, if you want to be a professor, it's probably not going to work. Figure a year or two for you to catch up on stuff you've forgotten to take the GRE, 6 years in grad school then post docs, maybe a faculty position in ten years, and an additional 3-5 for tenure? It seems pretty unlikely that you'll ever cover your opportunity costs.
I dunno---unless you're doing a PhD to prove something to yourself, you're probably better off doing something else.