2) Plastic is not recyclable in a lot of jurisdictions. Seattle stopped collecting it all together.

3) Most people will not ecycle things. Most people will just throw them in the trash instead of driving to a big box store to drop of headphones for ecycling.

3a) Sure, this behavior is common across electronics (being lazy, throwing away) but when you design an electrical device to never be repaired you are just making things worse.

"It would cost more than it's worth to like... break it apart, to open it up, and replace the battery" (because we designed them that way)

Have you ever heard of planned obsolescence?

To your second point, the problem isn't that they come from recycled. The problem is that they won't be recycled again.

And that's not even addressing the issue of the charging curves of lithium batteries that make those batteries fail sooner than they should.