Yeah, because the Greek μαγκες thought they should have to pay those loans back.... Unfortunately for them they kept asking for more money (loans) because Greece was bankrupt!
When the world markets would not lend Greece a single dollar, given how risky this was, the EU still gave Greece loans with low interest rate but with the stipulation Greece would repay most (not all) of what it owed. Where's the trap? or the exploitation? That's why several EU countries were 100% against giving Greece any new loans.... Oh, we cried laughing when some "geniuses" said that Greece should go back to the drachma.....? a worthless currency that nobody would accept at a time when Greece imports almost everything.... tsk.