If experienced professionals make more money than fresh graduates, things that are affordable to the average person may be unaffordable to the average young person.
If people accumulate wealth over their careers, young people are at a disadvantage when they try to buy a home.
If young people can't find stable jobs with good career prospects near their friends and family, they need more financial stability before they feel comfortable having children away from their support networks.
Some of these issues can be alleviated by redistributing wealth from middle-aged people to young people. For others, it may be necessary to tune down the competitive meritocracy and expectations economic efficiency.