As a centre left I very much like his rhetorics and thinking, but you have to be extremely careful to take any of this at face value. I was not immediately involved but close enough and involved enough to the action to read and discuss these topics at least 1-2 hours a day over the course of late 2010-2014, so I would still not consider myself an expert, but I do have a rather good feel for how the discussions moved and changed.

The truth is, there was at the time no attractive option. For too long the Eurozone countries' governments delayed taking a hard decision (and so did Greece btw), and if you think back to the discussions and insights of the day that was maybe not the ideal but usually the most realistic, feasible and often also the most sure approach. The problem was that this went on too long, more and more intermediate measures were taken to try and counter the crisis, with billions given to Greece and many more promised if needed. Each time this involvement got bigger and chickening out less feasible . Then the Eurozone governments made a huge commitment and let go of probably 2/3 of their demands (which were mostly sound "stop spending and finally make sure you get all the money in that you sold theoretically be getting, i.e. fight tax evasion, etc) and finally things seemed to calm down for a few short months. Prospects looked good, Greece was sorting out some of the mess the last 8 or so governments had created.

THEN, after years already of this torment and depending on your calculation somewhere from 50 bn up to 400 bn Euro being given to Greece, syriza, which was the absolute extreme left any party across the EU could be, got elected. They had campaigned with posters of Merkel with swastikas and Germany's finance minister as Hitler. And they, a party that in the past had never been >5℅ or so, got the top job and this fringe far left economist named varoufakis became finance minister and lead negotiator for Greece.

The election campaign was nerve wrecking and threw the country into chaos, the result even more. By the time they took office the gains of confidence etc had already disappeared completely, ratings for anything Greek kept spiralling down and bad news came from Spain, Portugal and Italy.

Varoufakis mostly spent his time giving insulting speeches and interviews. Then he went to the finance minister meetings, said no to everything and kept insulting and lecturing them. This is not an exaggeration. His party went back on a huge part of the agreement that had bought Greece billions in aid. Eg they started hiring huge amounts of officials, reverted firings, went back on the promise to sort out their probably messiest pensions scheme in the world, etc. All that being in direct contradiction to Greece's signed and agreed terms.

And then they started negotiating again. The third or fourth deal, and each time Greece failed uphold it's side of the bargain but got billions. Hard bargaining while things kept deteriorating. Some rough deal is agreed while the Greek government keeps lying about the demands by the other countries. Greece's government announced a referendum with a very weird phrasing as bargaining tactic and campaigned for the people to vote against the EU's new (and again much lightened) conditions. The vote was against (!) the new agreement. And three days later, after pretty much three days of finance ministers and leaders battling in meeting rooms, Greece signed the agreement. And again got billions. Varoufakis was sacked as he immediately started criticising everything again.

Varoufakis, personally and with the rest of his party, has probably cost Greece at least 5℅ of its GDP. His solutions sound great in theory but are impossible in practice - either because they are just thought experiments of "what could have been", or because they just demand things from the other side (in particular the Germans) while promising little in return. You have to also remember that Greece caused this whole mess themselves. They faked statistics just to get into the Eurozone and continued to do so for a decade. And the one honest government that revealed it and generally started sorting out decades of overspending and cronyism got punished at the polls to a degree hard to imagine. In particular the Germans are very unhappy with the way they have been branded for trying to save the union while trying to get the Greeks to, if they are not able to be accountable to themselves, at least be made accountable to the countries loaning them billions.

This was not about saving German and French banks. That was one worry, certainly, but this whole effort was an attempt to save the EU and the Eurozone and all of Europe from doomsday. Maybe Greece could have exited the Eurozone without too much pain. Or maybe all Greek citizens would have lost their savings, all banks been obliterated, the economy completely destroyed and the country thrown down to a developing country level. The effects for the remainder of the EU were equally unpredictable. No one knows today and no one could have known then, claiming anything else is simply dishonest. And certainly no one dared to make this wager...