Welcome to earth. Here outside the US there are countries that recycle up to 35% of plastic waste and intend to recycle more through regulations on types of plastic used and improvements in processes. https://www.scb.se/en/finding-statistics/statistics-by-subject-area/environment/waste/waste-packaging/pong/tables-and-graphs/recycling-targets/
It’s not dwindling, it’s not dismal and it’s certainly not pointless.
To bring it back: choosing to not recycle your plastic because you think only 5% of it will get recycled is indeed as stupid as throwing away your pizza crusts and thinking it doesn’t contribute to food wastage.
Or, you know, someone in need nearby. There are homeless people eating out of garbage and families using food banks everywhere. But then you’d also look like an asshole for just giving them a bunch of crusts instead of a whole slice.
How about just not buying more food than you can eat? Or save a couple of slices for the next day? Or give someone else a slice before you fill up on the inner circle of your plate of food?