I'm like you trying to break into prop trading (Ms applied mathematics) would you think it is still possible to 'make a career' in this kind of stuff? Or would you advise getting a PhD first? How was your experience at the prop firms?
Put concisely: if you can't handle seeing a smaller paycheck next month because a guy on your team pressed the wrong button and lost $50k in 10 seconds then trading is not for you.
If you want to get in I would recommend as much math and programming as possible. A PhD probably isn't necessary, an MS from a top school will do. You'd better be prepared to do programming, math, AND arithmetic in interviews, though. I once had a options trading interview that included ten "please multiply 148 by 72 in your head, we'll wait" questions.
Sadly this advice only applies to USA... E.g. UK has such an over-abundance of IT workforce that tech salaries are significantly below US despite comparable cost of living.