The only evidence needed is to just drive on the roads.

I do agree with OP that the internet is filled with tons of bots and shills, and has been for a while.

However, there are absolutely a lot of stupid people out there. The whole NPC meme that hit a few years ago highlighted that a whole lot of people don't have inner monologues. Through extensive debates, that I've had and seen, to research into conspiracy theories, seeing how people react when their ideas are challenged, it's obvious that there's a large section of the population that aren't creative. They're more like human robots, that are programmed, and merely repeat what they've been programmed to. If you challenge their beliefs, they merely repeat their programming. You could present them mountains of evidence to the contrary, and they'd reject all of it, with ease. They even get angry at you for daring to change their programming.

At a certain level, it has to be wondered if that kind of person is somehow beneficial for human populations, because it's either a majority of the current population, or a very large segment, that it's somehow a genetically selected and predisposed behavior, somehow benefitting the species. Because, if society were healthy, these people would be (hopefully) parroting the truth, defending it. However, since the liars took control, all they do now is repeat and defend the lies. That, or what we're seeing is conditioned, meaning not natural, either through diet, chemicals, brainwashing, or a combination. It could also be a consequence of the rise and fall of civilization. When civilizations peak, the people are comfortable, with numerous barriers erected between themselves and nature. This prevents stupidity from being rightfully punished and weeded out. This stupidity grows, and will get big enough to weigh down civilization, where it will slowly at first, and then accelerate toward collapse, because of the stupid. This is almost always paired with corruption, too, where the corrupt take advantage of peak civilization, and gain/retain power through dumbing down the population, or intentionally trying to make us dumber, usually by feeding us lies.

In any case, objectively, there are a lot more stupid people put there today than there were 50 or 100 years ago. Then again, there are still also a great number of good people. It's just that they're largely drowned out by the stupid and/or censored and not on social media. Social media has enabled the stupid easier access to spreading their stupidity, and it's arguable that social media attracts the low and mid wits more, especially in the normie spheres of the internet, which makes it appear like the stupid is more common.