It is unlikely that gun owners are simply unaware of the studies that prove the dangers of guns. They may not have studied them, and they may reject them, but the arguments they make to rebut the truth show that they know the truth is out there and that other people acknowledge it.
Part of the explanation is that some gun lovers desperately want to feel safe and they are willing to believe that guns will provide them with the safety they seek. Once they accept gun ownership as a solution to such an essential need as safety, they let gun ownership become so important to them that they are willing to defend it regardless of how nonsensical their defense is. Gun ownership becomes a matter of faith for them which is not vulnerable to attacks that are based on what is real. It is like the magic feather that Dumbo the elephant thought helped him fly.
It might seem that, if gun ownership has become akin to a religion, its adherents would not feel the need to defend it against reality-based arguments. Religious adherents don't generally feel they need to prove the existence of a deity to non-believers. Faith, after all, is beyond objective proof. I think that gun lovers try to defend their love of guns because they don't want to admit to themselves or anyone else that they are trusting their fate to something as mundane as an inanimate piece of metal. They don't want to think of their guns as being their idols. They want to think that their belief that their guns will protect them is rational, not supernatural, spiritual, magical, or superstitious.
Some gun owners get more than a feeling of safety from their guns. Guns make them feel powerful, and even dangerous. With guns they don't have to feel intimidated; they can be intimidating. Guns change them from thinking of themselves as potential victims to potential heroes who might be able to protect not only themselves but also other vulnerable people. They can be the bully, not the wimp. If they have to sacrifice intellectual integrity for such an intoxicating transformation, they are willing to pay the price.
Many gun owners also get a new sense of identity when they become part of the gun community, and a feeling of belonging. Gun owners are very affirming of other gun owners, and people who demonstrate that they are pro-gun by renouncing the facts about the dangers of guns gain instant acceptance in gun-loving groups.
The reasons why gun lovers turn a blind eye to the facts is that they get what they want from guns, despite the facts. If they faced the fact that guns make them less safe rather than more safe, they would no longer have anything that would make them feel safe, they wouldn't be able to feel powerful, they wouldn't feel like they belonged. They would be back to feeling vulnerable to the uncertainties of life. Who wants that? Sure, they could develop more faith in their fellow human beings and in their god, but that takes some effort, and there is no well-funded, powerful, national lobby comparable to the NRA to assure them that everything will be OK if they embrace humanity and life. For gun owners, it's easier to just buy a gun and ignore the truth.