It is sad that the sort of bigoted opinions you're espousing here are what us firearms enthusiasts have to endure. It has nothing to do with machismo, nothing to do with Obama, and nothing to do with birther garbage.
The right to bear arms is a right of last resort. Its the right that protects all others and, as such, it is the _most_ essential right.
As for naming incidents in the last 100 years where armed resistance to the United States government would have been productive or useful, I recommend you look up the forced internment of Japanese Americans during World War 2. I also recommend that you read about the Black Panthers standing up to corrupt Oakland police and marching on government buildings, loaded guns in hand.
You don't have to be a crazy conspiracy theorist or a right-winger to realize the thought that "something like that couldn't happen in America" is naive at best.
edit: I omitted an "n"