I should mention with respects to the sustainability of the Greek pension system. Before the crisis, there was supposed to be enough money in those funds to keep the pension system going. In 2012, the Greek government in an effort to reduce their debt, had the pension funds, invest their money in Greek bonds, which it later haircut by 78% this was as part of the PSI. At the same time, bankers and other networked private bond holders were warned and allowed to sell their bonds back to the bank of Greece before that happened. The same happened to Greek Universities, hospitals, and other funds that held large amounts of money that they used to run vital infrastructure. As a result, the revenue burden from pensions rose exponentially for the state since now they had to fill the deficit from the pension funds using tax revenues, they then begun reducing the pensions again.
The pension funds were always a subject of much controversy though. They are administered by the government which decides how the money is invested. In the past there were examples where the government took money from pensioners by having them buy Greek bonds to 'fund' expensive construction projects to clients of the administrators, or executives investing the pension money in their own affiliated enterprises.
This is of course part of the problem rampant corruption and significant windows for administrations to do what they like. In the end of the day however it is the pensioners who worked all their life that were punished by having their life plans destroyed. Workers in Greece also don't get to choose whether they want to contribute to the fund. So it ends up being a massive fuck you to every Greek that worked hard in their lives all while foreign media call them lazy or that they should just deal with it.