You forget the power of propaganda to get people to act contrary to their own best interests.
How many times have we seen comedians do bits where they ask passionately animated protestors/supporters basic questions about the issue they are so passionate protesting about, only to get blank stares and painful silence back?
That has always been a fundamental weakness of democracy, that is why when democracy was first practiced by the ancient Greeks, only (educated) land owners could vote. As democracy was expanded to become universal suffrage, the problem was exacerbated since anyone with a pulse can vote. In any society, you are going to have exponential more idiots than smart people. So it doesn’t take a genius to figure out that if you can corner the brainless idiot segment, you basically win democracy.
A free media is supposed to help safeguard against demagogues and such manipulation, but that in turn has been perverted and made into a tool of manipulation itself. A free media is meant to be a media free of political interference and undue bias. But that has been instead perverted to mean free for the rich to buy up and make into their own personal lobbying service.
It’s no accident that the west is currently experiencing the weird anti-education, anti-science regressive trends that we are seeing, because the less well educated the population, the easier it is to manipulate them into doing stupid things that benefit the elite even as they obliterate their own interests and welfare.
Brexit, the rise of Trump and vaccine hesitancy are just the most obvious headline grabbing recent examples. There are plenty more the deeper you look.
So, to sum up, interests are no longer eternal when the west is concerned because powerful vested interests can now fairly reliably manipulate western electorates to vote against their best interests.