I hear you but I think you're discounting how much millennials are accounting for this drop.
Student loan debt, credit card debt, job outsourcing, automation, skyrocketing healthcare/housing costs, poisonous music, poisonous social media has caused a lot of despair with millennials. It's also led to a lot of young people not seeking relationships. I'm telling you years from now people are going to look back and wonder why we didn't do more to help this generation.
I actually think Gen Z peeped game and are making some better decisions (studies show they are saving more and accumulating less student debt) to not fall in the same pitfalls as millennials and live a better quality of life.