Like in the real world, we have yens, euros, dollars. Imagine having only 1 currency
Wouldn't it be great?
Not all country have the same system, and not all coins are created equal so get that idea of one coin or one currency, it will not be great and will be a lot of conflicts, people should get used to having many coins but always research for the right coin to invest, Bitcoin and the majority of the coins are open source, and people can always create a clone.