25 is around the age when you start seeing the consequences of the bad choices you've made during adolescence.
About the most one could say about 25 is that it's when people's paths start to radically diverge, even amongst the group of people that were previously lumped together as "high achievers." So perhaps the subset of that group who are relatively low-performing — and yet, somehow, high in self-awareness — will wake up and start making changes at 25.