Because the fed-ral government dresses up as ducks, and if i do not have my semi automatic rifle the ducks from washington will come and make me pay taxes without representation.
There was a guy shot here the other day who had his pants stolen by the suspect. I wear really nice pants, so in the event I fail to disarm the suspect, I would prefer to have the right to shoot him, in the arse, as he is running away.
The interesting thing is, the video doesn't mention the reason that the buybacks and confiscations happened in Australia, and when you consider that guns in America kill about a thousand times as many people as the Port Arthur massacre per year... to me, lobbying for the right to keep guns seems to be actively against the public safety interest.