That's very misleading. The phrase "more so" could not possibly have any meaning in this context.
First of all, IQ is a statistical concept. It only measures overall trends.
Secondly, IQ suggests that intelligence is 1-dimensional. But it's not. Different people have different strengths and weaknesses. That may translate into being great at one kind of math, but not so good at another kind. Maybe one person will have a great geometrical intuition and someone else may have great technical skills. One person may have an exceptional memory and another person may have unbeatable concentration and focus. To the extent that IQ even measures intelligence, it tends to average all these things out into one thing, and in doing so, it loses too much information to be that useful of a concept.
Thirdly, we live in a world where people are not taught how to use their brains effectively. Because of this painfully obvious and absurd lack of emphasis on HOW to do things effectively, we often frame things in terms of talent and hard work as if those were the only two things that are involved, in blatant disregard for reality. In fact, it's initially impossible to tell the difference between "talent" and just having happened to be doing things the right way by dumb luck. Or perhaps the more intelligent people are better at finding the right way of doing it. But it can still be taught.
Genetics play some role. As does upbringing, which, after the fact, you have as little control over as you do with genetics. But there are other very important factors to being successful.
