Ok I can understand that many of them maybe did not actually like Hitler and were just following orders because they were afraid (I doubt that but I accept it as an argument) but it is still your homeland, your capitol your civilians your families there... how could they just retreat to the west instead of going full "this is sparta" mode inside the city with whatever they had?
Can you clarify OP?
Do you mean those German forces outside of Berlin itself(like 9th and 12th Army, 3rd and 4th Panzer Armies, or scratch forces like Detachment Steiner) and why following the Soviet breakthrough on the Seelow Heights they didnt try harder to relieve Berlin itself?
Or the German forces left in Berlin and why they didnt just fight to the death?
Though on a minor note about defending "their homeland, families, etc" its actually worth noting the composition of the final holdouts in Berlin. The forces garrisoning the central government district were not very German at all. Defending the Chancellery and Hitler's Bunker were the remnants of the Nordland and Charlemagne SS divisions, so Scandinavian and French troops, along with other remaining cadres from other units.