This is the answer. Everyone wanted to make "... but on the Internet" because there was money in it. Then everyone wanted to make "Facebook, but for..." because

This is the answer. Everyone wanted to make "... but on the Internet" because there was money in it. Then everyone wanted to make "Facebook, but for..." because they could get money. Now everyone wants to make cryptocurrency or do blockchain stuff because people are still willing to spend money on it. It's the hot new thing, there's a frontrunner but not an established winner, and investors are still willing to give people money for it.