Because no one buys something and then doesn't bother to learn to operate it at all.
Its the "at all" part that gets people into trouble. For many things there is a difference between
thinking you know how to operate it, and actually knowing how to operate it.
"its a gun, how hard can it be?", is actually something some people think they know, and do not.
An autopistol is simple. Several simple steps. That MUST be done correctly, and in the right order. So is a revolver. But they are different steps....