What ruined Dorsey for me was the crypto nonsense. I didn't use Twitter but it seemed like he was the typical asocial self-loathing nerd for a while. Then he went full on savior-syndrome and tried to use Twitter as a marketing tool for NFTs and cryptocurrency, more or less signing the platform's death warrant. I don't know a single person that actually enjoyed Twitter's brazen embrace of crypto.
If he was still a bumbling nerd with a sympathetic plight then people would have an easier time defending him. But his aimless endorsement of radical nonsense is basically a mirror to Elon's own behavior, unfortunately. I don't trust Dorsey with power anymore.