What scares the world of cryptocurrencies?

In the Second World War, the victorious countries established a global financial system that they had to impose their domination over world economies through the International Monetary Fund, whose purpose was to assist in the reconstruction of countries affected by the effects of the war. The Bank's policy on interest-bearing lending has been adopted by rich and rich countries to lend to poor countries. Thus, countries begin to pay interest on loans for long years, which may limit their development because of the increase in interest rates. The world's economies relied on foreign currency, the currencies of the IMF's lending countries in trade such as the US dollar and the pound. These currencies were pegged to gold and precious metals at the beginning and when the dollar began to swell as a result of the Vietnam War, world oil prices were pegged to the dollar.

Digital Currencies
The digitized or encrypted currency, headed by Bitcoin, is a virtual currency which is not monetary and does not supervise the printing or issuing of any central bank. Digital currency ownership is documented in encrypted records stored on computers. Bitcoin was established by an anonymous person named Satoshi Nakamoto, and began trading in 2009. Bitcoin does not rely on a broker or a central register. The currency is traded between the seller and the buyer without any intermediary. The digital currency is registered in encrypted records around the world. In other words, no one knows how much your money is, not a bank employee, government or anyone else.
For example, if you go to a store and buy a piece of clothing and pay by credit card, the bank is the intermediary between you and the seller. Even if you pay cash, the central bank is the mediator where it issued the currency. If you use the digital currency, for example, when buying a piece of clothing, you pay through a digital wallet saved on your mobile phone and the seller has a machine similar to the payment machine with credit card, you pay directly to the seller. When the process is done, ownership of the digital currency changes from your portfolio to the seller's portfolio. The change of ownership over computer networks around the world is soon spread in a decentralized way called Blockchain . That is, there is no computer or central bank operating or aware of the parties and that no change to a transaction performed over Blockchain can be made without the approval of the seller and the buyer together.

How does Blockchain work?