They are addicted to the feeling of power they get when sneering at something/someone. Whenever they say "clown world" they feel like Jim from the Office staring directly at the camera--as if they are in the know, the most informed ones, the superior ones. That plus the comment sections of these videos give them a rush from both them posting and getting likes, and seeing their existing views get articulated by others--that rush of validation is hard to come by IRL.

They aren't necessarily miserable in the traditional sense, in the first person, as long as they are not directly doing introspection or evaluating how far detached from everyday people they have made themselves. Usually the craving for these feelings of superiority/validation comes from them trying to mute some deeper insecurity and inadequacy they are avoiding facing up to at all costs.

For instance a lot of judgmental puritanical people are also frightened of the possibility that they can't hang with the cool crowd and cannot make themselves likable in social settings, so adopting the worldview that those who can are actually just "mainstream," sheep or forbearers of civilizational collapse enables them to cast themselves as righteous/principled for not participating in the worlds that they'd felt excluded by in the first place.

The harm these people are ultimately doing though is what is known as "self esteem debt," mentally placing themselves on pedestals they did not earn through any real-world action, and having to retreat to ever more demented circles and echo chambers to sustain the feeling of being on the right side of something--leaving their own self development stagnating, letting their insecurities compound rather than be unpacked.