I think one point that has to be borne in mind is that the Euro was not essentially an economic project but a political one.
The conditions for entry were fudged. The only two countries that satisfied the strict criteria for entry were Luxembourg and the UK and we didn't join anyway. The others just massaged the figures.
Currency Unions can't really work without political unions and certainly can't work with widely divergent economies.
My feeling is that many of the original movers of the project were quite aware that it would lead to terrible problems in the future, to which increased centralisation of power to Brussels could then be put forward as the solution.
To some extent they have got their wish, with EU-appointed puppet governments now in place in Greece and Italy, and the EU basically running the Irish economy.