Most Americans support common-sense gun regulations, like banning assault weapons and red flag laws. It's just a sign of our broken politics that support doesn't translate into policy.
because enough Americans ( even if they may support certain "common sense" regulations do not trust the government to stop with that. Therefore, people look at those numbers of people dead and look at just how few people die in mass shootings and decide that that may well be a risk worth taking as for the most part gun deaths are either caused by a person's own hand or by gangs/ otherwise during OTHER criminal activity. The same activity of the people who would have guns no matter what you do.
For example, in 2021 the latest data I found there were about 48-49k gun DEATHS that means deaths caused by a gun in any way shape or form not just particular situations.
Of that better than half maybe up to 2/3 were by the person's own hand ( most of whom did not take anyone with them sad yes but not the "mass shooting" that regulations will supposedly prevent.
Another hunk were gun deaths caused in the commission of some other crime ( The people who would have guns one way or another from the black market which these regulations would flood guns into, by the way )
You had some that were caused not in the commission of another crime (probably a small percentage, but were caused by someone's anger at a particular person in many cases if a person has that much hate for someone (especially someone they know well which are probably most cases they will just find another means and there are A LOT of means of killing someone if you want to badly enough.
There are gun deaths that are caused by failure to follow gun safety ( accidental) which in most cases by the way are punishable(
Finally, you have justified homicides which are just that cases where one person kills another for a justified reason ( usually this is some form pf self defense or defense of other though one could argue that in cases pf the castle doctrine self defense plays a smaller role, but it is still not completely not self defense as the thinking is people do not force entry to/enter without permission other people houses. In fact, some states, I believe actually do require that if the entry is not forced it may not be a family member ( I am not sure about that) and even that only applies to the entry if the family member becomes violent to the point you fear for your/another's life you may still use lethal force .
It is of note as well that most shootings and even many "mass shooting" under the way it is currently defined are carried out not with assault weapons or even long guns, but with handguns which happen to be the same guns that generally already have the strictest regulations ( at least in terms of getting them to begin with and even in carrying them. Most states ( even that do not require a permit require a person ( non-military) to be at least 21 to carry a weapon concealed and in many places ( this may be federal law) I am unsure but you have to in at least many places be at least 21 to purchase handguns from dealers and yet those are the guns not long guns or even assault weapons that lead to the most deaths (the same guns that are the hardest to legally obtain.
Do not misunderstand my first paragraph I am NOT saying (and no one is) that the gun deaths are not sad only that when I look at that total ( and the causes/ motivations that make up that total and I compare that to the number of guns and legal gun owners in this country the amount of shooting that those regulations would be targeted to is really a TINY percent of a fairly small percentage of the causes of death in this country.