system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: If Bitcoin was such a huge breakthrough because of digital scarcity then why are cryptocurrencies like dogecoin, darkcoin, litecoin, etc., constantly being introduced?
gpt
the stuff we use for money all over the world and throughout history doesn't usually have much value itself.  just paper or metal or wood or glass or shells.  it's only valuable WHEN we all agree with each other that it does have value, and that we will all use it.  the more people that use it, the more valuable it is.

of all the coins you mentioned, so far, bitcoin has the largest number of people who agreed with each other (by paying for it, or offering to trade for it) that it has value.

the others have value too, but it's less.  the only reason it's less it that less people have it and use it (less people agreeing its valuable).  who knows, if more people started using feathercoin than bitcoin all over the world, then eventually the total value of all feathercoins put together could buy more than the total value of all bitcoins put together.  doge is a great example- dogers are using it all over he place, splashing it around, buying pizza, tipping each other for fun, etc.  just by going nuts with it they made it pretty valuable in a super short time.

they are all scarce to various degrees (actually doge is least scarce because i think they agreed that there will never be a set limit of dogecoins).  but it's not the scarcity itself that makes it valuable.  it's the scarcity + the agreement among everyone.