It’s not a sports team mentality. The CEO pretty much disparaged a lot of users who were actively engaging in profit-making ventures for Reddit. Moderators, being unpaid spam filters, were lauded as entitled brats (landed genetry). He also explicitly got mad that people were using “his” content, content that Reddit never made yet is happily wants to profit off of. He did all of this while basically calling third-party app developers leeches despite them making apps with features Reddit’s native app lacks.
People want to see Reddit fail because Reddit pissed off the people that generated their value. People want to see Lemmy succeed because it is federated and cannot be abused like a central platform.