There are indeed cultural issues, but deeper than that is the problem of trying to impose one economic policy (via one currency) on an area as diverse as Europe

There are indeed cultural issues, but deeper than that is the problem of trying to impose one economic policy (via one currency) on an area as diverse as Europe. We are generally quite good at rubbing along with our European neighbours, but the race to expand the Eurozone at breakneck speed has led to a large number of economically disparate countries being lumped to together as (somehow) one entity. Like easy credit, it only holds together while the trend in the worldwide economy is upward.