I suppose work hard on learning, deeply understanding and practicing as much math as possible, and trying to make novel discoveries / models. I'm certainly not a Tier One mathematician, so I'm probably not the best person to ask. Maybe it requires people to be born with some innate ability, although I'd certainly like to hope it doesn't. Regardless of whether it's actually achievable or not, however, it's definitely a worthy goal to strive towards if you want to be a good quant/trader (and a very intellectually stimulating one).
A nice post on the topic by someone who most certainly is a Tier One mathematician: https://terrytao.wordpress.com/career-advice/does-one-have-t....