There are people wired like Tao (or superstar athletes, supermodels, or other remarkable people) that don't achieve the same results.
Even among the people who have similar "luck" in that respect, some still stand out. The people we think of as elite performers aren't just elite relative to the 99% of us. They're also elite within the top 1% that makes up their field: they're dominant even among the people who should be their peers.
There are very very few people wired like Tao; how many child prodigies like that are there ? He seems to be one in a million but its pretty much impossible to assess IQ at those levels. Sure, it's not enough. YOu need the obsession for math, but lets not trivialize his intellectual ability - he's definitely not only top 1% that would just put him in the smartest 2-3 kids in his class. No, he was probably among the smartest 10-20 kids of his age group in the whole United States.