BB guns can shoot your eye out.
So can a sling shot. Where there’s no fire there’s no firearm!
My late father was hit by a BB in one eye. Eventually in his his fifties or sixties, he was diagnosed with macular degeneration in that eye but not his other eye. Fortunately his retinologist determined that the macular degeneration was stable and not getting any worse over time. Dad had lots of trouble with his vision in that eye as he got older. He had a cataract removed from that eye but didn't get much improvement in vision in that eye. He was afraid to have the cataract in the other eye (not as cloudy) removed for fear of diminishing his remaining eyesight.
BB guns are not toys. They are supposed to be used to learn how aim and shoot guns and learn gun safety. They should never be pointed at people. They don't have enough power to reliably stop or kill someone for use in self-defense, and they they have the capability of causing serious injury.