Not being a citizen of the USA, it is not for me to say.
US citizen or not, you have every right to give an opinion.
Having looked at a range of sources it appears that the US has the highest rate of privately-owned firearms in the world - the global 2018 Small Arms Survey put US gun ownership at 120%, meaning there are more guns than people. Add to that the weak gun laws, which Trump made weaker when he reversed a law introduced by Obama making it harder for people with history of mental illness to purchase firearms - and then as mentioned above, after one of the various recent mass-shootings, he said guns weren't to blame, mental illness is. You can't make this stuff up.
Most gun deaths in the US are suicides, and most homicides are individual ones not the mass shootings, although while the US has less than 5% of the world's population, it has 31% of mass shooters.
While there are countries with higher gun-homicide rates, among developed countries the US is quite high up the list, in the top 6 I understand. The others are nations such as Brazil, Guatemala, Colombia, Mexico, Venezuela which have various kinds of economic problems and weak institutions such as their criminal justice systems, issues the US doesn't have. What is it in the American pysche that causes such a relatively high rate of gun deaths? Those opposed to stricter gun regulation repeatedly say that guns aren't the issue, people are. Even though the broad availability of guns, and the tenacious belief in the right to bear arms, both contribute to this issue those people are in a sense correct. The guns don't discharge themselves. So in some ways Martinus you are right, whatever the constitutional issues might be, there is clearly an issue of some other kind at work here, that makes so many US citizens trigger-happy.
As to Trump's possible re-election, I do think it is unfortunately a very real likelihood. While the Dems regained some ground in the mid-terms, that is not going to be a magical solution. Dems 2020 campaigning needs to happen asap and at the moment they don't seem spoiled for choice for candidates. We even have Hillary Clinton indicating she might run again. I quite like her, but thought in 2016 she might not win - the Clinton 'brand' has outlived its shelf-life and I don't think running again will help.
The emergence of Sarah Palin 10+ years ago sowed the seeds of accepting high-profile politicians being unashamedly bullish, stupid, unsophisticated and hardline. Trump's success is the result, helped by wall-to-wall media coverage the like of which most candidates can only dream of, something that continues even now. His unfiltered aggressive undignified words and behaviour are very popular with great swathes of Middle America who are unbothered by his constant lies and self-contradiction, and his complete disregard for etiquette and the conventions of state, his staining of the office of President. With the Dems so far providing little or no realistic opposition, I foresee another 4 years of DT.