I have read the answers, and I must say that I still don't understand the subject.
It is not really important, that you can't use gold for paying via the internet or buying a dinner in a cafe. Bitcoin is not suited for this well to, and this feature not needed for using the main aspect of bitcoins - storing relatively big amout of money, for accumulating money for e.g. buying a house. If we buy bitcoins or gold for storing money, this means that we "lend" money to other people with relatevely honest conditions (more honest than lending the money to banks).
I have found that the price of gold has increased twice in last 5 years. So why it hasn't been a common practice in USA/Europe to purchase a gram of gold each month?
We can say that people in Europe don't know that are the bitcoins and this is the reason they don't buy them, but they must know what is the gold.