My work is with smart people, a first from a top university is not by itself enough to get you noticed in our process. A little bitter rivalry is between one of my directors who got the 2nd best first in maths from Oxford, and the guy who got the top.
I only see "successes", since those who crash and burn never make it to our radar.
A clear thing for them is moving from being the brightest person they've ever met to being "good but not great". We've got a few thousand "bright young things" in our set of contacts, and they have shit like "came 2nd in Chinese Physics Olympiad", "Swiss award for gifted young people", and in one (true) case "had the choice of a Nobel prize or a huge pile of money". Our typical BYT is offered a British passport by right simply by being clever enough, yes, really, it can be done, "highly skilled migrants", we've got hundreds like that.
The point here is not the quality of our DB, but the size.
Your G&T may be very smart, but as a child even mediocre adults can outclass him, and he gets used to that. But he notices that his peers aren't in the same league as him and his world view makes him at least a bit singular. For him to be happy and confident, that "singularity" needs to be felt to be a good thing, else he's "peculiar".
Thus there is a shock coming for young G&Ts.
Some don't take it well, and in my view a big part of the value of G&T programmes is to get them used to kids of the same age who will outclass them, or at the very least not be all that impressed.