Again, experience beats academia. These courses do a great job at introducing you to how mathematical modeling works. You need to go through an incredible grind (I can't stress this enough, it's a GRIND). I would recommend having a solid foundation in analysis. I can't stress how important this is, it's pretty much your bread and butter. I never took any computational finance courses, I wasn't a physicist, but a pure mathematician.

I will say this: from my experience, there is no such thing as a genius. Anyone can be a great mathematician, and gain this skillset. Often times, these so called geniuses from Ivy league schools are over inflated. You will get stuck, and get stuck for weeks to even months. It takes a very special mindset to push through it and those are the minds that are the most successful. Math is hard, no one is naturally gifted at it. You may have had people in your past that you thought were geniuses. I assure you they weren't. You saw them solve "easy" problems. They weren't anything special. Mindset always trumps innate abilities.