>But the old parasitise the young in the West

I mean it starts to happen everywhere where life expectancy dramatically raises. If before you died in your 50s or early 60s you didn't have much time in your life that was unproductive by age alone. When you add that the uplift in life expectancy occurred in a time of just massive technological change, a rapid acceleration in the industrial age where the work of labor was shifted to machine capital.

>takes the form of older people just being free of various forms of society’s needs

Again, before this a lot of old people died terribly in the streets of starvation and other easily solvable things.