What groups are their own worst enemy?

I can’t imagine any group being more their own worst enemy more than gun owners.
They rant on television that if we try to take their guns, they will kill us. They send ricin infused letters to the President and to members of the government. They claim we need more guns in our schools to protect the kids. People are killed every day by gun owners.
I know many gun owners, and they are not all nut jobs. Most are very responsible, but they resist the most reasonable restrictions.
In short, gun owners are their own worst enemies.
What other groups are?