> Also, most of the ocean plastic comes from a small number of rivers in the less developed world. [1] Rich countries aren't really the problem.

That reference isn't exactly justifying your statement. AFAICT that research is just comparing the relative amounts of plastic going to the ocean _from rivers_. Rivers are not the only way that plastic gets into the ocean.

Most of the ocean plastic is actually from fishing gear...so if you want to reduce ocean plastics your best bet is probably to stop eating so much fish: https://www.nationalgeographic.com/science/article/great-pac...