My point is simple:

We as a society can regulate effectively, but bans have always been completely and totally ineffective.

There's a long history in the US of rum running, drug smuggling, and other dodges, and there are too many intelligent people who see a buck to be made if they can avoid John Law. Heck, we even smuggle 3L per flush toilets, and there's nothing customs has been able to do to stop it.

As a society we're extremely skilled about getting around bans and prohibitions of all sorts, a gun ban would just be one more avenue to make money.