Hello Olaf, interesting view point, thank you. People can easily do shopping with cash without using banks today. This gives them a great privacy advantage, you're right. However, in a world where we switch to digital payment systems, our preferences and personal information will be in jeopardy as long as our personal data is associative. If we come to the situation that cryptocurrencies reduce the amount of cash circulating in the market, do you know what percentage of the money circulating in the world is in cash form?

"People are earning and spending money without ever touching it. In fact, economists estimate that only 8 percent of the world's currency exists as physical cash. The rest exists only on a computer hard drive, in electronic bank accounts around the world." (https://money.howstuffworks.com/currency.htm)

In my opinion, although it does not seem possible to switch to digital currencies in the near future (due to the technological development differences of the countries), it is possible that the problems you mentioned may arise in countries that adapt completely digital systems to them.