It's probably a lot more than just one thing, or another.

There are a great many people who simply have no intellectual curiosity. People with zero interest in seeking out and verifying new information, who feel no impetus to figure things out for themselves, or who resent those more knowledgeable than themselves because they see that information asymmetry as a personal attack. People who aren't curious about anything are idiots.

The issue that you describe- intellectuals treating idiots like idiots, is probably rooted in years, or decades of one-sided conversations, or trying to hold conversations with people who don't feel the need to argue in good faith. At a certain point, low information people with low curiosity are a burden to engage with, let alone attempt to meet as peers. I'm not saying that's right, but I can understand it.

For those who retain curiosity, Education and exposure are probably the best way to thwart the rise of idiots, which is probably why public access to high quality information and education resources have been massively curtailed, and/or monetized to the nth degree over the last 40 years. There is a distinct correlation between broad idiocy, and declining quality of life in industrialized nations, and that has certainly been the paradigm in the US.

So, we understand where the idiots are coming from and who benefits from their lack of understanding, we just need the idiots to understand WHO is depending on their remaining useful and WHY they have been denied a path toward bettering themselves. And, of course, the crux of the matter is that idiots cling to their idiocy as an integral aspect of their identity, which means any real changes will have to be long term solutions, wherein children of idiots are allowed to break the cycle leading to better understanding and insight. But there are challenges inherent in that evolution too, as you underscored poignantly; it can be stark and lonesome and heartbreaking for children to realize that their parents are idiots.