When a 25-year-old lands a senior role in 10 years at 35, it's because someone else's 13-year-old grew up, graduated college, and got hired as a junior. Promotions are 10% Crushing It, 90% dumping your grunt work on some poor sap too young to know better.
Society is a pyramid scheme, and, like all pyramid schemes, bringing more people in is ultimately more valuable than actually selling the LuLaRoe or whatever.