Then the GFC happened, and so many European nations became insolvent. Germany HAS the funds to bail them all out, (and indeed the GFC has not much affected German business profitability) but individual Germans are bitterly resentful that their careful and clever money making practices are being asked to fund several nations that have collapsed under the burden of collective debt. They want iron-clad guarantees that if they bail-out places like Greece, that their money WILL be repaid back to them. For Greece and other insolvent European nations to engineer successful repayments, even long term, from the starting point of where they are, public spending has to halve, throwing millions out of work, halving the pay-checks of the rest, and reducing pensioners, students and the unemployed to such depths of poverty they will all have to move if paying rent, and stop buying anything but food. Hence rioting in Greece, and continual government turn-over and bail-out delay, as the Greek citizenry refuse the needed austerity measures to get them solvent.
The simple truth is that Greece can't become solvent in the short or medium term. Steep asuterity will send, and has been sending, them into a downward spiral so that they need even greater austerity to pay back their debt, and so on. I doubt it'll take long before most of the professional classes take advantage of the free movement of persons to get the **** out.
Insisting on crippling austerity is a terrible way to get your money back, but a great way to destroy a nation.