I believe that allowing citizens, or even more specific humans, the right to bear arms is a good thing. It does however come with repercussions like with these mass shootings. I don't know all the specific laws in each state as they vary but I believe we should really be more thorough on who we give guns. I don't know if any state does this but maybe require some kind of psychological testing along with the usual background check to ensure that the person isn't mentally unstable.
I do believe that the government kind of fucked itself over with the second amendment. As I told zmart, there will always be illegal guns in circulation. Whether it's from before certain guns were made illegal, self-made, or imported. The only way that the government would be able to "sort" this is to forcibly take the weapons away from every single citizen or household. However that would impede on the second amendment and would be taking away the right to bear arms. This may cause shootings all across the country as the government attempts to take all the weapons away from it's people. Then again, even if the government did succeed in taking all the weapons, people would just end up making more themselves or try to get them imported. At that point though, guns would have been made illegal and anyone found with a gun would be arrested or maybe even shot on sight. And finally ofc if the government impedes on any of the amendments, the people will start to lose their faith in the government possibly causing it to topple.
I know I probably went off topic but I like to theorize what would happen if these situations arise. I'm not really trying to change your mind but more so just showing what could happen.