I have been tall my whole life. I've always been the tallest kid in my grade, sometimes the tallest kid in the school. I topped out at just under 6'5, which is not absurd, but it is solidly above-average.
I was never an athlete superstar stud(though I did grab all the rebounds in blacktop hoops, which always meant something), I am not particularly intelligent(don't think I'm dumb, but I'm nothing exceptional). I was never great with girls, and I grew up being relatively shy.
As much as being tall can be an advantage, I think that it can just as well be an inhibition. If you are tall and uncoordinated, or tall and lanky. Your chances of being picked on are just as good as if you are short and ugly.
Any outlier runs the risk of being ostracized for their uniqueness. Even if that uniqueness is something that we think of as being positive(beauty, intelligence, athletic prowess...etc.)
Basically, if you stand out at the extreme, your ability to relate with your peers can be compromised, which can lead to a host of other issues.
It is not uncommon for naturally 'beautiful' people to have the worst self esteem problems. Or for very naturally bright kids to be alienated from their peer groups. Or even for talented athletes, who can succumb to borderline psychotic competitive desire, which can mess a person up if they don't win.
No genetic advantage is going to take the place of having the right mindset, the right work ethic, and the right attitude. The elite performers in the world tend to be the rarest combination of naturally gifted paired with socially mature. They also are almost always blessed with extraordinary circumstances and surroundings.
Also, being above 6'3 is not a cakewalk. The world was not really made with people 6'4 and up in mind.