Because far too many Americans have not yet forgotten their world history and what happens to those who are disarmed.
It wasn't that long ago that Democrat Presidents had US Citizens of Italian, German, and Japanese ancestry disarmed, their property forfeited/confiscated, had them rounded up, and were forced at gunpoint into concentration camps under cruel and harsh conditions, watched over by armed military guards.
They will have to kill us. We are free men, and intend to stay that way. We will not comply.