Most economies are built on the assumption that there will be more young people than old. If that assumption ceases to hold true without some active planning to

Most economies are built on the assumption that there will be more young people than old. If that assumption ceases to hold true without some active planning to deal with an older population there will be too many retirees and too few workers. This problem is almost certainly solvable with some planning, but humanity as a whole isn't always good at that.