It like gold or the US dollar. you can convert it easily to fiat money. Not every country can cash ETH OR LITECOIN , you need to convert to convert it first to Bitcoin
Then also there is its high value, what alt coin is valued at above 2000 usd ?
Gold is valuable because it is worth more than 1000 usd. Other metals are rarer or more useful. But gold is what we use as one of the foundation of our financial system
Basically value of a coin it not always what can it can do but what value we assign to it. And we place value on US DOLLAR, GOLD and BITCOIN