I think you haven't been paying attention if you think people shooting guns at the public, or at cops, is an "extraordinary circumstance" in America. It's not just mall shootings, or parkland. It's also people just shooting at cops after getting pulled over for speeding, which is far less likely to get national news attention.
You're free to ignore it, but I added the point about grizzly bears because you seemed confused how a gun can help defend you against someone with a gun. It can help defend you against many threats, in fact.
Edit:responded from the account on my phone, sorry for any confusion.