I'd say there's two related bad habits: 1: making exclusively unverifiable predictions, and 2: expecting or acting as if you were expecting to be more accurate in your unverifiable statements than in verifiable ones.

edit: those two often go together. There's a huge supply of cheap verification in the homework sections of the textbooks. Armchair physicists barely tap into this supply. edit: and by barely I mean pretty much none ever do.

Topics such as Amanda Knox trial or LHC finding the Higgs, it seems to me that for such predictions the dopamine pleasure of success is larger than the feeling of failure, and the betting on those is thus somewhat wirehead-y. May still be good for calibration though.