This was one of those completely unusual weekends where the news on Greece finally opened the eyes of many investors that many things could still could unexpectedly go wrong in the near future.

Maybe it could be helpful recalling long-term investors a monetary union (eurozone) and its single currency (euro) only has a chance to succeed when the union is backed by a “single” central bank and a single monetary policy while at the same time the union is governed by a single political, legal and fiscal authority, which is certainly the case today.

Until that form of combination becomes a reality, which is still not on the horizon, the monetary union of the eurozone will remain an unfinished ambitious undertaking that will remain at risks from the “inside.”

That said, after we had in 2013 the first bank holiday in the eurozone in Cyprus we now have again, only 2 years later, a bank holiday in Greece.

According to the IMF, in 2014 Cyprus had a GDP of $22 billion and Greece had a GDP of $238 billion, which was roughly 10-times that of Cyprus.

Of course, there is no comparison whatsoever between these two economies, but it’s noteworthy in Cyrus’ people could during the bank holiday and thereafter withdraw 300 euros from the ATM machines per day while in Greece this has now been fixed at 60 euros per day for all Greek citizens.

Believe me, that doesn't bode well!

In simple words, all this means the overall situation in Greece is “catastrophic and chaotic” while keeping in mind Greece is still member of the eurozone as well as of the EU.

I don't think it's an overstatement saying Greece is in real terms facing conditions similar to a poor emerging country that is out of funds.

I don’t think the chaotic situation has reached its maximum level yet (I hope I'm wrong), and the catalyst for that could come next Sunday when the Greek referendum that has been called whereby the Greeks will have to make it clear if they accept or not the latest fiscal reform proposal from its creditors.

Anyway, and notwithstanding Greek Prime Minister Tsipras has urged Greeks not to approve creditor’s bailout proposal, first polls show most Greeks favor the creditors’ deal.

I think, there is a serious chance Greeks will vote with their purse on Sunday.

Whatever comes out on Sunday, the final result as well as the whole chaotic situation at present will have caused deep damages to Greece and the eurozone as well as to the EU project, which doesn’t mean Greece and its creditors are at risk of reaching (on Sunday in case there is a “No” vote) that proverbial point of no return.

Purely financially spoken, we’ll have to wait and see if Greece will pay its debt obligation to the IMF on Tuesday, and thereafter in July its debt to the ECB, and so on… and so on…

One thing is for sure, Greece cannot repay its debt in a serious way (= without tricks!) as its debt is still above 175 percent of its GDP while its GDP contracted again in Q1 of 2015.

Besides that, we’ll have to wait until Wednesday to see if the ECB will remain Greece's banks lender of last resort through the emergency liquidity assistance (ELA) facility and if the EU policy makers will try this week to “bend” the rules as defined by the EU Treaties to keep Greece afloat and inside the eurozone.

Maybe, what could be a sign of things to come, early on Monday the yield of the 2-year Greek Treasury jumped by 53 percent to 33 percent, up from a 22 percent yield at the close on Friday. 

Interestingly, U.K. Prime Minister David Cameron said on Monday: “Britain’s interest will be best served, particularly in these times of great uncertainty, by an agreement between the Greek government and the eurozone that delivers the security and stability that we want … we need a eurozone that works.” Keep in mind UK will hold a referendum about yes-or-not staying in the EU.

One thing is for sure, volatility will be back this week.