Guns laws are the stated assumption that every citizen in a nation is a criminal in waiting, that any person shouldn't be allowed to own a weapon simply because every citizen has some potential to go out and shoot people. "Gun culture" is the same as any other material-culture-community. They buy fancy toys and tools that do cool things and go out to shoot them. No different from the lockpicking community, or the science-hobbyist community. Secondly, guns are an icon of independence. A gun held on your person is a powerful tool and a security against incidents like this. Perhaps not literally, as I know of few times that terrorists or similar are stopped by guns, but figuratively, in that the people with the guns feel safer, the control is in their hands. The US is all about power, it's all about capability. People here are prideful when we say that no nation in the world could invade, and hold, the US, because every last citizen is able to take up arms and defend ourselves. That's why gun culture is such a big deal, it's an icon, a way of life, a meaning. These shootings, they are becoming a bigger issue, but guns have been around for ages. Something is wrong, and it's not guns, it's media, it's culture, perhaps it's the attitude around guns, who knows. That's what needs fixed, not the freedom to have weapons.
Other countries have some element of 'gun culture' - shooting/hunting clubs etc. It's not something I'm interested in but I can understand the allure, sure. I think what bothers me about home is the widespread nature of it. A substantial portion of the population owns guns and I guess I just don't quite understand that. Perhaps you are right in that there needs to be a change in attitude around guns, sure, but I really do think that it should at least be some more regulation. But I admit my opinion might be different if I grew up around guns and had respect for them as an outlet/hobby - I guess I don't. Thanks for the context though, definitely something to think on.
One thing that is important to remember, as well, is that almost everyone will reasonably agree to guns not being able to be resold, or needing to have ID and criminal background checks before buying a gun. The problem is that the debate constantly gets phrased as TAKING THE GUNS AWAY! by the people who really are disrupting progress for little reason but political support. Not necessarily that existing US gun culture opposes any restriction. That's my experience though.