> Democracy could only work effectively if most of the population is very well educated ... as ignorant people are much easier to manipulate

I don't think that's true. In order to manipulate lots of little people you have to manipulate a few big people first.

Look at the elite levels of nearly any group that comes with some kind of social status (e.g. celebrities, political parties, university faculties, media organizations) and you'll probably see remarkable levels of groupthink and political monoculture. I don't think that's because all the individuals in the elite group are more educated and enlightened and therefore all naturally came to the same correct conclusions about everything. Seems far more likely that most of the individuals are unconsciously or consciously (if they're Machiavellian, which many of them are) trying to "fit in" with whatever they perceive to be the dominant or "correct" ideas and behavior of the elite, so as not to be expelled from their number, and further that outsiders who wish (consciously or unconsciously) to join the elite group will tend to do the same.

The groupthink in itself might be resilient against attempts to manipulate the elite group's culture, and it definitely is when it comes to fast and/or drastic pushes, but you could reasonably hypothesize that groupthink is weak against gradual manipulation because it's ultimately based on consensus rather than any core principle or truth. And elite groups are, by definition, smaller than the overall population, so if your goal is merely to influence the culture of an elite group, there are fewer people you need to target. Vanishingly few, in fact, if you can identify the subset who are actually influential and not just following along.

So in a democracy, especially one with mass media and/or widespread social media, if you can influence the social status elites enough to change their perception of the correct way to "fit in" with each other, votes will tend to flow in the same direction simply because humans are naturally attracted to and desire social status.

Another way to look at "fitting in" is "wanting the right things." Get the elites to want what you want and the broader population will tend to follow. See: https://en.wikipedia.org/wiki/Ren%C3%A9_Girard#Mimetic_desir...

The countervailing force is that some people, either by nature or circumstantially, hold a default skepticism of elites and authority.

Controlling a democracy (assuming you can't just flip votes) therefore requires two parallel efforts: you have to influence as many elite groups as possible (gradually, so they don't notice [assuming you can't just buy them off]) while simultaneously exalting them as noble and trustworthy to increase their visibility and tamp down skepticism. You have to buttress the overall system of social status hierarchy. Buy-in from the mass media helps, but luckily they're already fully convinced of their own importance.

The side effect is that you end up creating room for malevolent actors within the elite groups to commit heinous acts with impunity, often using gatekeeping as a coercion tactic, but if you're convinced that your ultimate goal is just, you'll probably still be able to sleep at night. (And maybe a Ronan Farrow will come along every now and then to help with that.)

The counter strategy is to undermine faith in the elites and/or the overall social status class system, e.g. through mockery, which happens to be both more persuasive and easier (and, arguably, true, in that many people occupying elite social strata are indeed ridiculous). But that damages the control mechanism and is thus unacceptable.

Point being: democracy doesn't really work as intended, not because of lack of education in the electorate, but because everyone, top to bottom, is prone to envy.