Should I throw away my mom's insane amount of grocery bags?
Why does your mom have so many grocery bags? She sounds like a hoard.
She doesn't like to throw any away because she thinks she'll be able to use them for something.
I understand  why you think your mom shouldn't keep all those bags, but you can't just throw them away. They don't belong to you, and I'm sure she'll be annoyed if you get rid of them. I think you should talk to your mom about the number of bags she's hoarding, and maybe she'll get rid of them herself.
I have talked to her numerous times and it never led to any results.
It's really hard to get through the mind of a hoarder because it's a mental disease. Maybe you can try seeking professional help from a therapist or doctor that specializes in hoarding. Maybe they will know a good solution to cure her hoarding.