Michael Pettis: I think Spain [and all the peripheral European countries are similarly uncompetitive] will leave the euro because it seems to me that the country has already started on the self-reinforcing downward spiral that leads to a crisis, and there is no one big enough to reverse the spiral.
How does this process work? It turns out that it is pretty straightforward, and occurs during every one of the sovereign financial crises we have seen in modern history. When a sufficient level of doubt arises about sovereign credibility, all the major economic stakeholders in that country begin to change their behavior in ways that exacerbate the problem of credibility.
Of course as credibility is eroded, this further exacerbates the behavior of these stakeholders. In that case bankruptcy comes, as Hemingway is reported to have said, at first slowly, and then all of a sudden, as the country moves slowly at first and then rapidly towards a breakdown in its debt capacity.

Colin Twiggs is a former investment banker with almost 40 years of experience in financial markets. He founded PVT Capital (AFSL number 546090), which provides income and growth strategies to wholesale clients.
Colin also co-founded Incredible Charts and writes the popular Patient Investor newsletter.
Using a top-down approach, Colin identifies macro trends in the global economy and then combines fundamental and technical analysis to evaluate opportunities in sectors that stand to benefit.
Focusing on interest rates and financial market liquidity as primary drivers of the economic cycle, he warned of the 2008/2009 and 2020 bear markets well ahead of actual events.

That’s one item, not two, nor is it a reason, it’s a description.
That is merely an extract. I suggest that you read the entire EconoMonitor article.