I won't even attack the current political head for the US, I think the problem is way deeper and as with anything, to solve a problem, you need to strike the root.
To answer crenn's question:
"Why carry a gun? A whole police officer is too heavy.":
Lets say somebody has broken into your house and is threatening your physical well-being or the physical well-being of one of your family members or other occupants of the house. Which one is more effective:
1. Pulling out a rifle, pistol, shotgun, etc
2. Calling the police and waiting for them to arrive.
I am going to wager my money on #1, every time. I do not want to have to wait for the police to come and handle the situation (in the 5-10 minutes minimum drive time it would take from the PD to my house, even going balls out, assuming no traffic), in which time myself or my family/friends could get injured/killed. I would much rather pull a gun and either repel them (call the PD afterwords), or, if need be, kill them. If somebody holds any of my family members at gunpoint and refuses to drop their weapon when told to, I will shoot them, and, while a shot to injure and not kill would be preferable, I will shoot to kill if need be. No questions asked. I can and will not let myself sit by while people endanger those close to me, and I would not want the baddie ever getting the opportunity to commit crimes again, especially when putting others lives at stake. I couldn't sleep at night afterwords if I sat by and watched or let somebody kill or injure somebody close to me. No individual or group of individuals should have control over whether somebody can live or die -- and I'm no exception to that -- but I'd much rather live with the blood on my hands than to know somebody else got away with something I could have prevented.
"Who do you call when the Police or government break the law?":
The entire reason for the second amendment is pretty simple: Allow people to defend themselves against the government. You can not rely on the government to protect you and your best interests in every situation. Government has it's flaws. Citizens need to have the power to stand up against the government when the government is wronging them. I, in no way advocate resisting police officers, but if I see police doing something blatantly inappropriate and illegal (like raping somebody, or lesser extremes), again, I am going to stand up and do something about it. Again, this idea of standing up for the greater good. I'll be less keen on the idea of harming a police officer, but it's the same thing as above. If I don't stand up for what I believe is right, I don't think I could live with myself.
"I would rather have something and not need it..."
"...than need it and not have it."
I pray that I will never have to take aim at somebody holding a family member at gunpoint. I pray that I will never have to intervene and stand up for myself or anybody else being wronged by the government or police. But as much as I don't want these things to happen, they could, and I'll be damned if I'm not prepared and I don't take action. Simple as that.
So crenn, that's why, I at least, believe in owning a gun.