being optimistic is fine. but its also important to be realistic.
its all about expectations: if you're hoping to get an academic gig anywhere and dont care about location, money or institution/department quality (in the traditional sense) then you have a much higher chance of being satisfied. The stronger your preferences, the more likely you're going to be unhappy.
Unless you've got a good plan B that you're happy with - it really does help one sleep at night!