It's was an avoidable clusterfuck.
There's so many reasons why the situation deteriorated. I'll give the TL;DR version
Greece is a country that's responsible for about 1% of global GDP. What's made it a possible trigger for another financial crash was bank interdependence due to bad management, corruption and greed. Basically- due to the qualities of several financial instruments nobody knows where anyone else's money is. This makes a default with bonds of any country/bank/company potentially toxic for the person who
could be holding them.
With this context- Greece matters. European banks are still knowingly holding Greek debt. Many more people are unknowingly holding it and a massive quantity is held by the E.U itself (as part of it's bailout program). If a disorderly default happens (experts haven't decided yet) a 'credit event' would occur. this would make stockmarkets everywhere shit themselves.
There could be a repeat of 2008.
Since the way the euro (E.U's disaster currency) is structured doesn't allow any of it's individual remembers to devaluate themselves, Greece was in trouble. (Short backstory- Greece hid the extent of their debt load prior to 200
A council of individual creditors, the IMF and the rest of Europe was called upon to create the 'troika'. They would sort out Greece's deeply inefficient economy and correct bad economic policy. An important side goal (
argued by some as the main goal) was keeping Europe's banks afloat and protecting the periphery countries from economic contagion. The economic 'medicine' was a truckload of austerity, none of which brought the country back to growth. Greece currently has had 25% unemployment for 5 years and almost no help, since the bailout funds were being funneled to European banks to deal with their red balance sheets.
The trokia humiliated Greece because it was more convenient to keep Europe afloat. That was a massive error of judgement. Two technocrat government endorsed by the troika fell to SYRIZA: A coalition of the far left
aka neo-communists. Unlike ADF, tumblr and a slue of western hipsters- these people are the real deal and every attempt to control them failed. After 5 months of wrangling, Tisparas (the president of Greece) had one last trick of his sleeve. At the last minute a referendum on the terms of the bailout was called- It would be decided by Greeks themselves. Due to the hilariously bad timing of this move
Greece defaulted to the IMF and slid out of it's bailout program.
This whole farce is a testament to the arrogance of the E.U and how our financial system is built on sand.