I'd also like to add anecdotally that a lot of people develop burnout at that age, probably because they keep pushing themselves and/or get sucked into their own enthusiasm / passion instead of set limits and the like. But then, I also think people get less resilient to stress and the like after 30, less able to compartimentalize or bounce back quickly.

What you end up getting is people ~10 years into an exciting career where suddenly they can't perform or cope as well as they used to. But they can also be in a pretty senior position by then and be pushed out of their comfort zone.