Examples are all around us. Some of it, though, IMHO, isn't stupidity. There are a lot of deliberate acts going on that appear stupid to someone who actually wants the country to prosper. I think we have many in elected office on both sides of the aisle right now who want to see the USA fail.
There are ordinary citizens (and non-citizens residents) who want the USA to fail. These are mostly rich spoiled brats who think they will be protected as members of the elite ruling class. The rest are poor dumb kids who believe everything their leftists teachers tell them and think it makes them “edgy”, “trendy”, “hip”, and “smart”.
Forget about the polls. There are a large number of leftist idiots who keep their beliefs hidden until election day and these filth are all around us. The USA WILL die of this infection. It is beyond anyone’s ability to treat or cure.