American culture thinks that murder is OK Well it may be quite reasonable to arm oneself for the purpose of self defense against those, that, because of their ignorance and unhappiness, may want to harm you.
That's just human life, really. One can be quite philosophical and thinking deeply while walking down the street, maybe even feeling happy, resolved and care free, and then some driver mounts a sidewalk shouting allahu akbar trying to take you out (and not to a restaurant), or any other cultural message they may want to convey.
So there's that possibility.
In terms of tyrannical governments these have always arisen in our human history, and one of the things they first do is take citizen's weapons away to make it less hazardous for them.
Essentially it's planet of the apes, this earth.