It is a fact that the US are a monumental outlier with respect to gun-related violence. Compared to other developed countries the US are not an outlier in terms of mental health and poverty level. It has also crime rates very comparable to other countries. The only very striking difference between the US and other countries is the number of guns available to the general population.
These are the facts.
How and if to act on the facts is a matter of political opinion.
Guns are a constitutional right in the US. Reducing the number of gun deaths would probably require repelling the 2nd amendment and a constitutional change cannot be taken lightly. As someone has pointed out, being shot is a relatively unlikely cause of death, in particular if you do not live in the wrong side of town (and there is not a gun in your household). So it is a very legitimate stance to maintain that 20000 deaths every year is an acceptable price to pay for the constitutional right to own guns.
Other people think that these are unnecessary deaths and that gun ownership should be restricted in some way to bring the number of guns to a level closer to that of other developed countries. If repelling the 2nd amendment is the only way to meaningfully restrict gun ownership, so be it.