I agree. My PhD is technically in CS but it made heavy use of algebraic topology. Being 5 years out, having worked briefly in tech, then at a national lab as a software engineer has given me enough outsiders' perspective on pure math. You probably need to work as a professional mathematician to be at the research frontier of a given area, but otherwise the fundamentals of math are unchanging, and in my opinion, that makes it accessible to anyone who is sufficiently interested in and passionate about math.