Actually, it was your banks (including perhaps your central bank) lent to Greek banks (including presumably the Greek central bank) a mountain of euros. Where that money went, it is not clear; but anyway the Greek government, that had been elected by the banks, decided that each Greek citizen had to fork 500 euros to pay your banks. Which was the bankers' aim all along: take more wealth from the general public.
Trouble is, the Greek citizens were never asked whether they agreed to any step of that plan, not even told clearly what the plan was.
You talk as if Greece goverment didn't borrow anything for paying the welfare state. You talk as if the Greeks were being forced to subsidy Greek bank's losses from a private operation.
I have seen how it worked here. Today 60% of the government's revenue goes into paying interest on the public debt, which was created by criminal borrowing by the neocon government, 20 to 12 years ago (and only keeps growing). That borrowing came together with austerity measures (= taking more from the people, giving them less) and radical privatization (= giving people's property to banks for a pittance). Few citizens at the time understood what the government was doing, and only when the damage was irreparable did they get a chance to change their government.