This was all about 10 years ago, the market has moved since then, and now it seems you can slip under the PHD radar and do similar work if you classify yourself as a "data scientist." Some of the mythos around quants and technology has been uncovered, 10 years ago quantitative and electronic trading was still a newish thing and at a backseat to traditional traders and PMs. Many firms these days are technology first, though there are often still walls between those who write "models" and those who write "infrastructure."

Anyway, its still largely true that for "quant" roles you need a PHD. It doesn't need to be in anything particular, but Physics/Math/Statistics are strongly preferred. This is just a hiring screen thing. Its not impossible, but quant types tend to have a big head and be elitist, and I personally found them to just be real jerks in the hiring process, and there were plenty of opportunities opening up in the then lucrative algorithmic/HFT space so I went down that road. By jerks, there were just several opportunities where you could just tell they didn't like my lack of credentials and that I went to a state school (on a scholarship, but still they can't have non ivy leaguers stinking the place up), and it was also fairly easy for them to just throw advanced math problems at me and knock me out of the running- regardless if this was something that was ever used in their actual work.

I don't really regret it, but it would have been nice to be more heavily involved in pure finance stuff- I find the markets fascinating, I was very happy when I wrote some of the first TWAP and VWAP strategies out there, and then later (surprise!) started getting edged out of that space by "quants" with PHDs.