Isn't the "smart contract" aspect of Ether supposed to make it useful? I've read a little about it, but have spent more time lately learning more about bitcoin so I don't know the specifics or if it's mostly puffery.

One of my friends has invested early-ish in Ether (a few hundred shares just <$100), he has hopes of becoming a millionaire off of this investment as he expects/hopes for Etherum to overtake Bitcoin in value at some point. Another friend who has been in the space longer says he may make $100k+, but the likelihood of supplanting Bitcoin and him becoming a millionaire is very, very small. He says if Bitcoin were to crash/be replaced, all cryptocurrency would suffer and be devalued. Is that a likely true statement? Why is this scenario different than other economic situations?