Optimistic, as in if you have 2 differing indications of fuel you believe the higher value?
What planet are you on?
Read what is written. I wrote :-
Even if the fuel gauge suggests you have fuel in the tank it seems a dumb trade to believe one instrument over another and allow yourself to be more optimistic
As in if the fuel gauge suggests you have a full tank but there is a Red "low fuel" warning. I think most would assume the worse.
What planet are you on?