This is the thread that made me make an account and what a pain it was to find without having saved it anywhere. I've been holding out for someone to say it, but havwn't seen it specifically.
Single use plastics. I still remember the weird feeling of doom when learning the world population and making the quick relation to disposable plastics, constantly being told "but it's only a little bit." A little bit for several thousand years, per billions, is too many bits.
The best way I've found of making people realise how much waste they generate is to ask them to imagine having to bury it in their back yard. Every week.
That's pretty much what we do: bury it somewhere else.