I have a PhD in Biomedical Engineering, and am working as a DS for the past several years, and I can tell you that there is a hard ceiling for many of us out there, because we don't have enough of a math background (I'm looking at you "Real Analysis") to ever really understand the "deep theory" that someone with a PhD in Statistics or Math (or hell even a BS in Math) can have.

However, having said that, I still consider myself a very productive DS, and I get stuff done. I'm not going to ever be on a research team at Google, but those aren't the only kinds of DS jobs out there.

And I'm not just plotting stuff.