On MSNBC's The Last Word with Lawrence O'Donnell, Costas stated,
"[The gun culture] demonstrates itself in the Wild West, Dirty Harry mentality of people who actually believe that if a number of people were armed in the theater in Aurora, they would have been able to take down this nut-job in body armor and military-style artillery."
As someone who grew up around firearms, I have lots of fond memories that involve firearms. I remember getting my first BB gun and shooting it in the backyard with my dad. I remember buying my first .22 from a family friend (with my dad's permission) with money that I had earned. I have given and received firearms as gifts for special occasions. I have introduced new people (including my kids) to firearms. I have put meat on my family's table with a firearm. I have picked up a firearm when someone was pounding on my door at 2AM in a less-desireable section of town. At no point in any of this did I hurt anyone. This is my gun culture.
When people are new to firearms, or they have questions about a particular firearm or getting their carry license, most people in the gun community will bend over backward to help them out. It is not uncommon to be at a range and have someone offer to let someone else shoot their gun if they've asked a question of expressed interest in it. That is my gun culture.
Back to Costas's comments, I do not carry because I harbor some Walter Mitty-esque fantasy of being a hero. I carry a gun for the same reason I have a fire extenguisher in my house: duty. I have a duty to my family to take care of them. That includes getting them home safely. I don't know if I could have stopped the Aurora shooter (who was NOT wearing body armor, and whose "military-style artillery" functions no differently than President Teddy Roosevelt's Remington Model 8), but I know that if I were trapped in that theater, I'd rather have a gun than not have one.
My gun culture is one of responsibility and self-reliance. What is the matter with that?
For further reading/viewing on this subject, I recommend Katie Pavlich's article here and/or Mr. ColionNoir's video here.