We are 'the germs'.

Over-population
Declining resources
Climate change reducing species diversity in flora and fauna.Else triggering deadly pandemics
So that's the slow death scenarios

Else politics of declining resources or some religious conflict triggers a nuclear war.
Quick death scenario.

Good news for storage companies though. Back in the 70s, if short of household space, people could safely leave their surplus possessions outside their homes, safe in the certain knowledge that they would remain permanently untouched. Indeed many passers-by would even add to the collection with their own items, as a kindly gesture.

What do we think it was about this particular halcyon period - generally seeming to be held to be from the 30s to the 70s or thereabouts (though I shall be sure to claim it for the 80s myself, as my eyes get misty) - that saw such a decline in houshold break-ins?

Evidently you couldn't leave your doors open prior to this period - otherwise no-one would have needed to invent the door lock - and, as we all accept, the crime threat is now so great we all must have several front doors, each protected with multiple locks, secured fast at all times (even when entering one's own home, which should only ever be safely attempted through a discreet upstairs window under cover of darkness.) And yet during that golden age, if it hadn't been for the climate, there wouldn't have been a door or window to be seen anywhere.

Must have been a grim period for key-cutters, though. Maybe that's why loads of them also do that work with shoes too. Cobblers?

Gizza kiss.

Smashing the granny out of cheap-labour prostitutes ?