The 1st 40years of my life i was told I had to worry about over population, in the last 5 I've been told I now need to worry about "demographic collapse"

It's not about infinite growth.

Given that not everyone lives to old age, we would expect children to outnumber old people even in a zero (or slightly negative) percent growth scenario.

I agree. I chose not to have kids for various reasons. And my "skilled" lol trade skills will die with me.

Right on. The way the way population is right now, every time a chunk of mountain or glacier falls down, or a river floods, tens of thousands die or are displaced.

In 1960 there were 2-3 billion people on the planet. Now it's 3x as many cars, mouths to feed, homes to heat/cool.

In Bangladesh there are over 1 million Rohingan refugees who've been there for TEN YEARS. They can't work there, have no country to move to, have to live on $6-12 a month for food.