The hidden logic in various human activities is often different from the apparent one. This is true in sociology, politics, economics. Consider NAFTA (North American Free Trade Accord), QE (Quantitative Easing: make banks richer so they be gooder), TPP (Trans Pacific Partnership: Terrifying Plutocracy Punishing China), etc.
For a decade the Greeks, having had their Drachmas converted into Euros at twice their natural worth, brought gifts to the rough Germans, by buying their luxury cars. Now Germany is rich and powerful, and Greece poor, and weak. Best conditions to pay for Greek arrogance.
There is totally no economic reason to keep on punishing Greece at this point. So why do the punishments keep on coming? One has to resort to a twisted psychological explanations.