They are the national currency of the internet to simplify in the extreme. Just like Japan has the Yen and Switzerland has the Franc, the web has Bitcoin and Ethereum as their native currencies. Bitcoin is already accepted on more than 1.2 million websites and online merchants.
Because demand is so high and the number of Bitcoins in circulation is limited (21 million total, so far only 16 million mined) the price per Bitcoin keeps going up and up, but the long term goal is to have a stable price for exchanges to take place and wealth to be stored safely and anonymously, because it’s no one’s business what you do with your money. That stable target price for most buyers is around 200’000 USD per Bitcoin.