The gemara says that Yerusholayim was destroyed bec of Kamtza and Bar Kamtza.
Um, what exactly did Kamtza do wrong?
Other than he is friendly with the nasty Baal HaSeudah, we never actually meet him in the story!
The BS was mean to BK, the chachamim didn't protect BK, BK's ultimate reaction was quite poor.
Blame them, Why is poor Kamtza being blamed for millenia?