SASless:-
Commonsense tells us that you negotiate from a position of strength....not weakness. (For you Brits....think back to Chamberlin v. Hitler prior to WWII). All Chamberlin obtained was some time to delay what was coming.
Hitler was intent upon War....was way ahead of Great Britain in its preparing for that War and thus felt to be in a superior position and in the end that Agreement was not worth the paper it was written upon.
That delay was what was needed to stop Hitler at the Channel. It meant that you Yanks had a base from which (with a certain amount of help from others) to attack Germany, with which you were at war (thanks to AH's inspired non negotiable declaration), to invade and liberate occupied Western Europe (with a certain amount of help from others), and then to occupy NAZI Germany (ditto preceding, yet again).
Are you saying that Chamberlain was wrong? What should he have done instead?