The basic idea offered by those supporting the Capitalist System is in their confidence that personal GREED will ultimately serve the wide interests of society. In their minds they think the more they succeed individually getting wealthier, the wealthier everyone else will become. The contradiction is evident in a system where competition is part of the way it functions, assuring always there will be many losing in their economic pursuits.
Yanis Varoufakis happened to be the Finance Minister when Greece went bankrupt and was then to confront the European most powerful Finance Ministers to solve a huge loan that had been engaged by the previous Greek government.
A currency of any country is like the flow of blood of their society, therefore sharing it with other economies of diverse strengths is difficult, as it happened to them in the European Union.
The EURO currency shared in the EU has been badly designed because it lacks the flexibility required of money within a single country.
USA having many states of different economic strengths can easily absorb the diverse levels of cash flow in it, while the Euro being used in a wide mix of economies with different governments and ideologies as Germany and Ireland and Greece is a recipe for conflict.