If Norway joins the euro, first and foremost, she will lose her most important asset, which is her national currency, that is, her sovereignty and control of her economy via her own monetary policies. That is enough to guarantee a downward spiral for the people of Norway, like every other EU country has experienced, except a couple ones -mostly Germany, that take advantage and gain a lot from the downfall of the indebted southern countries, like Greece, Spain, Ireland, Portugal, Italy, but even northern ones like France also suffer from the EU policies. Germany is in good shape (although even the German people have lost a lot), because of that factor and because of unequal treatment -like borrowing with zero or negative interest in contrast to those countries.
Meanwhile, the eurozone is very fragile and this is why Germany has bought huge amounts of gold the recent years. For example, recently Italy was prevented from taking a turn against the euro and its policies as is the wish of the majority of its people, with the president Sergio Mattarella violating the article 92 of Italy's constitution (which was considered a coupe), preventing Paolo Savona (an anti-euro economist) from becoming finance minister and suggesting a government of "technocrats" instead (=bankers). After the intense reactions of the Italian people, a second order was given to Giuseppe Conte instead to form a government, but Giovanni Tria, a pro-euro economist was given the position of finance minister, so EU got back the wheel of Italy's economy.
EDIT For those in doubt: Germany repatriated 700 tons of gold and became the second worldwide in gold reserves. World’s 2nd-Largest Hoard
Also: Germans Have Quietly Become The World's Biggest Buyers Of Gold
EDIT #2: The above link (Forbes) can only be accessed by turning ad blocker off. But you can access the source of the chart bellow. https://www.gold.org/research/market-update/market-update-german-investment-market
Those hundreds of tonnes of gold per year are bought mostly by banks and between them a national one (KFW) that is the main stockholder in companies like Deutche Telecom.
If the euro and eurozone is solid and has a bright future, why the strongest oligarchy in Germany buys tonnes of gold?
EDIT 27-7-2018: Nice website-policy, 5 idiots alone managed to gray-out the truth...