How are your quantifying that? You can look up the gross domestic product per capita for Greece since 1960 here:
https://www.macrotrends.net/countries/GRC/greece/gdp-per-capita
GDP per capita took a real dive after 2010. Still it is exponentially higher than 1960. 1960 was light years better than the 1945. From Wikipedia re: Greece and the end of WW2:
The country almost immediately descended into a bloody civil war between communist forces and the anti-communist Greek government, which lasted until 1949 with the latter’s victory. The conflict, considered one of the earliest struggles of the Cold War,[125] resulted in further economic devastation, mass population displacement and severe political polarisation for the next thirty years.[126]
Although the post-war decades were characterised by social strife and widespread marginalisation of the left in political and social spheres, Greece nonetheless experienced rapid economic growth and recovery, propelled in part by the U.S.-administered Marshall Plan.[127]
So how do you support your statement that "the misery Germany inflicted on Greece for example today might be worse than after WWII”?