I think you hve to look towards the future for the big answers.
As AI gradually kicks in throughout the western world people - especially white-collar workers - will find they have no jobs. There will be blue-collar workers needed, but these can be gotten from other countries; on the cheap. Now a person without work, and therefore on a some sort of national benefit scheme is not a great contributor to the nations tax pot. And just like the OAPs and unemployables, will find that the governments would rather they were gone. Far too much drain on the economy they might think.
So, they have to be gotten rid of. Of course, not just corralled into a raft and dumped way out into the sea. Or put into chambers that are then filled with a substance that kills them. No!! Of course not!! That would be barbarism in the extreme. But1 What about being blown up by a perceived enemy's bomb? Messy that. Far better to coax people into taking something that they think will do them good. Get them to crave for this thing even. Something that is, however. going to kill them. Maybe on the spot, or at the very least; prematurely.
And what might that thing be? Is it already happening?