A B.A. in math gets you to the forefront of mathematical research as it was circa 1912. (Source: https://slate.com/human-interest/2003/05/is-math-a-young-man...) This is purely my impression as somebody who switched away from pure math early in their career, but: amazingly, in pure math, unless you are really advanced, you are not even that close to engaging independently in cutting-edge research until well after your Ph.D. Math has been continuously researched by all the smartest people for hundreds of years (thousands, depending on how you view the dark ages). The low hanging fruit got gobbled up centuries ago. The same could be said for physics and various other "classical" scientific fields.