Tl;dr on Ethereum ?

Just head about ethereum around 3 days ago or so and read the FAQ in this forum, but some things are not explained well. People use it as a currency , but it is not a currency? Anyways, I am thinking about buying 100 ethereum for cold storage for 2-10 years, is it worth it ? Or will ethereum crash like the other crypt? Not sure why coinbase added ethereum as well.