Nicotinic receptors in the brain, like cannabinoid receptors, are named after the drugs that bind to them, not because the body is meant to ingest those substances.

“nicotinic receptors in an annoying way in the same way that cannabinoid receptors are called cannabinoid receptors but then everyone thinks oh you know those receptors are there so because we're supposed to smoke pot or those receptors are there because we're supposed to ingest nicotine no the drugs that's right right exactly receptor was named after the drug and so the important thing to know is that whether or not it's basal forebrain or predunculopontine nucleus or a locust ceruleus that at least in the brain because we're not talking about muscle where acetylcholine does something else via nicotinic receptors there in general it just tends to be a signal to noise enhancer”