As usual, the answer to the eternal question of “how much formal math training do you need for X” turns out to be “right around the amount the author of the argument has had.” Why is it that we always have to prove the instrumental value of maths education? You’re a lot more likely to “need” your maths in the “real world” than your Shakespeare, but few have much energy for fighting the idea that literature should be…
It’s a shame, too. As an undergraduate I had a very small amount of exposure to some papers in theoretical computer science. I presume they were fairly typical for the world of mathematics - trying to establish boundaries on how small something can be. And not much application in the real world. But I remember having my mind blown at the way the authors could take one problem, convert it to some completely different domain, and use previous work in that domain to prove things about the original problem. It was very beautiful, and I think even that very limited exposure has changed the way I see the world.
Then the real world came knocking and I haven’t been back since.