Why in the world do these things exist?

Legit what is their purpose? The bugs rate as one of the most annoying things in nature, and they’re freaking everywhere in every home. I’m in NYC, I’ve noticed the past few winters the houses are infested. They just wash your windows and crawl in this wondrously warm new “cave” we provide them. Thank you op for this great thread. Do they serve a purpose? I can’t see why they are around other than to annoy the crap out of us?