In one sense a crypto currency is just another tool for facilitating economic activity. Currency is not wealth, it is a just a tool that allows buyers and sellers of goods and services to easily transact their business without resorting to barter. Barter is inefficient for example how many pair of shoes must a cobbler make in order to buy the latest NVidia GPU? Not to mention manufacture them in the right color, size and quality etc. etc. You get the idea.

Security on the Internet is based upon public key cryptography also called asymmetric cryptography. I will spare the reader the gory mathematical details of cryptography and  crypto currency as they can be found elsewhere easily. It allows two parties that do not know one another and may not trust one another exchange digital data privately and securely. One of the benchmarks of secure cryptography is that the algorithms and code it is based upon are public. It basically based upon the computational difficulty factoring a very large number. The https: part of a url means use asymmetric cryptography for the initial connection and then use symmetric for data exchange which is very secure.

Trump's first crypto offering were his 'meme coins' that he and his wife brought to market in January. Trump is correct in that a 'cryptocurrency' can act as currency if a buyer and seller are willing to treat it as such.

Crypto currency requires just four things:

a blockchain for transaction logging

a hash algorithm for said block chain

a computer program to mine 'crypto' bits or a wallet for coins you already have

an exchange where actual currencies like dollars can be exchanged for coins

Bitcoin is deflationary as there is an upper limit on the 'coins' and is deflationary based on the halving algorithm that reduces the number of coins yet to be mined. The difficulty in mining and the fact that the number of coins have an upper limit is why it becomes more valuable over time.