it seems that many people have answered your question assuming that you're asking about becoming a research mathematician. But you can do a PhD in math and then go on to a different career, where you use your skills but don't necessarily go on to do original research. Many companies are hiring math PhDs and it seems to me that there are opportunities in very diverse fields. I'm not in the best position to discuss them ($p$-adic analysis doesn't seem to be very much in demand in the real world these days), but you should be able to find such information easily, maybe starting with the AMS?