Does he not realize that he's terrible at debating? Hillary crushed him in 2016 even if she did have some questions. He gets rattled from fellow Democrats, imagine what Republicans would do to him in the general?
Bernie really irritates me, because if he dropped out right now, his support would go mostly to Warren most likely and then we'd have a good race.
The problem is that the more people you have, the more "crazy" stands out. We saw it in 2016 with Trump. The outrageous characters stand out (remember when Ben Carson was leading?) while the "normal" vote gets split. If you took the votes for Kasich, Cruz and Rubio and combined them, they'd have beaten Trump. There were more "normal" Republicans, but they got split up.