Zuckerberg was barely adult when he started Facebook. And he probably bumped into a few older guys who thought they knew better than him, and history proved them wrong.
He likely developed some irrational belief that clever and young beats anything else, and saw an echo of his own bravado in Alexandr Wang.
Turns out his heuristics were not calibrated properly.
Didn’t he famously trash folks over 30 years back? He has really done nothing innovative outside of ads.