What I said wasn't idealism, it was dialectical materialism.

You're talking about class struggle but that doesn't contradict what I said, because class struggle was a part of what I said. And you had to cherrypick my comment to find a part of it that you could portray as otherwise.

When did I ever say "everyone gets together and the best idea wins"? I said it's a grueling struggle and victory isn't guaranteed.

But, as the course of history shows, although humanity takes a couple steps backwards for every few steps it takes forwards, overall it moves on a positive trajectory. Or else we wouldn't have made the progress that we have.

History has never been a struggle of ideas

History has always been about ideas, and you have to be very ignorant of the history of ideas to fail to see how they underpin everything that happens in an era. Whether we talk about Cartesian Skepticism quite literally defining the end of the Renaissance and the beginning of the Early Modern era (and giving rise to the scientific Enlightenment itself), or about the how the threads of existentialism underlie the countercultural movements from the beatniks to the hippies to the punks and beyond. It's all about ideas. What humans do is informed by the ideas that they hold.

By and large, the ideas underpinning monarchical forms of government did not survive the eighteenth and nineteenth centuries because the ideas of liberalism prevailed over them. Prevailed first in people's hearts and minds, and then in their decisions and their actions, and finally in political and military victories. Without the ideas, none of that later stuff would have occurred.

Nowadays we're seeing other ideas compete: in this context specifically, the ideas of neoliberalism versus the ideas of democratic socialism. Clearly the latter are gaining the edge, but they're doing so because first the ideas exist, second enough people are convinced that they could work that someone who will implement those ideas wins office, third they implement them and prove they work, fourth the ideas gain traction as people see that they work and the momentum begins to snowball.

It takes years or even decades. Bernie Sanders and AOC have been working at this for a long time, and if you can't see how the ideas they subscribe to inform their policy decisions, then I don't know what else to tell you. Do you seriously think they're just winging it without a clue what they're doing?

Liberalism didn't spawn the French revolution

There absolutely was an intellectualist movement which underpinned the French Revolution, without which it would have been disjointed riots with no shared conviction or cohesive structure, easily quelled and doomed to fail. All successful revolutions have been underpinned by intellectuals. That includes communist revolutions.

The ideas that we're discussing now, both mine and yours, are exactly that: ideas. You think the twentieth century would have seen the Soviet Union if the nineteenth hadn't had Marx and Engels?

Ideas inform decisions, and decisions inform actions. Actions without solid ideas behind them are lunacy. Actions require decisions, and decisions require ideas. It's not that hard to figure out.