As I recall, Andreesen's descent started with his being publicly criticized during the cancel culture movement of the mid 2010s. This seems to relate to that - perhaps the criticism came so hard he couldn't take it, and his solution was to refuse to think about it.
Someone decides you committed a faux pas, and people pile on, and this gets attention, which means the algorithm pushes it, and pushes the most inflammatory discourse around it. This creates a feedback loop that pushes things to maximum toxicity because, well, this keeps people on the app and seeing ads.
It worked with the nascent new right and Gamergate, and it worked for "woke" callout culture. The algorithm doesn't care about the angle. It just "likes" toxicity and lynch mobs because it drives engagement.
Algorithmic social media is a disease. It's an unmitigated net negative value for humanity, far more than even trash TV or tabloid journalism (due to addiction dynamics). It's like the fentanyl of the mind and the social discourse. If you work on it, you might be doing more overall harm than someone working on weapons. At least a weapon only attacks a small number of people at once, while this mass-lobotomizes the entire human race.
The best thing to do when targeted by such things is tell them to fuck off and close the browser or delete the app. If you engage, this drives the algorithmic feedback cycle. But all these guys are social media (esp Twitter) addicts.