This has already happened. Bitcoin has been forked many times. Also, there are literally thousands of cryptocurrencies. Bitcoin has the first mover advantage.

This has already happened. Bitcoin has been forked many times. Also, there are literally thousands of cryptocurrencies. Bitcoin has the first mover advantage. Craigslist makes 100s of millions of dollars every year. Bitcoin also has huge momentum with its network of miners and now some large institutional investors. It has survived 10 years with no successful hacks or 51% attacks. The market cap is almost 700 billion, so a lot of people have a vested interest in seeing it succeed. Botcoin not so much.