Intellectuals by Paul Johnson. He's one of the most well regarded historians period having spent years researching books with hugely expansive topics covering the history of Jews, Christians, the American people etc.
This book however is a deep dive into the personal lives and practices of twenty or so intellectuals who were highly regarded by "the Left" ranging from Jean Jacques Rousseau and Karl Marx to more contemporary types. Its not a scathing take down of various leftist ideology but is a very in depth examination of the many, many failings, flaws and fallacies each of these intellectuals possessed and really illuminates how these deeply rotten and flawed the philosophies and ideologies they helped develop were poisoned and ruinous from the very beginning.
Or as one of my Lefty friends said, "This book is basically one giant ad hominem."
Ya know... Potato... Patato... Still a highly recommended read if only to see the strong metaphor and parallels to the intellectuals of now. 🤷♀️