Well it's simple. An ideology swept the western world and hundreds of millions of people got totally consumed by it. For lack of a better name, I'll call it the "woke ideology".
The left have become so extreme because they're ideologically possessed by one set of ideas. They have lost the ability to look outside the concepts of patriarchy, critical race theory, queer theory and so on.
They have been consumed by a set of ideas. The same thing happened in Mao's China, Hitler's Germany and Pol Pot's Khmer Rouge. Luckily, this ideological contagion was not powerful enough to consume entire nations and result in violence.
You're the one talking sense Tessa. The left have absolutely lost their minds. They don't talk about healthcare anymore.