The corruption in the Greek economy was a drop in the ocean though. It had 5% growth per year, enough to outgrow its corruption like every other developed country.
They also said they will get the deficit under control in 2 years and a few months later said they would most likely default.
They had massive tax evasion problems (e.g. corruption) and one of the lowest retirement ages in the EU.
I'm really nor sure how you see corruption given that the government took out loans which it had no way of repaying even with 5% YoY growth. The simple fact is they were fiscally irresponsible. It's a common pattern in the Balkans to just do what is needed to win the elections without thinking of how the country is developing and what is the right course. It stems from the corruption of the political system.