It is a legitimate question. Even if you truly hate Bitcoin, why not go somewhere else and make positive contributions to something which is antithetical to Bitcoin?
You're probably overthinking it. Some people simply have too much time on their hand and that frustrates them. And instead of spending it constructively, by learning a skill, or building something, etc they rather vandalize someone elses work. Some of them hang in the streets, others on the internet...
As this forum is hardly moderated, and money-related stuff brings out the worst in people, it makes sense a lot of them hang out here. Try the same on the Ubuntu forums and you're banned in 5 minutes.