Ethereum did grow a lot lately, possibly due to other people using it as a mode of transferring their money. They can also be trading their BTC to ethereum due to it's recent price increase which also made it grow even more.
I think you're wrong. Let compare LTC and ETH , which come first ?
LTC ,right ? LTC ever stand in top 5 in coincapmarket !
Let's take a look on newcomer ,ETH and now it's reach top 5 in coincapmarket , you know what I mean right ?
Even Microsoft interest on ETH so I won't be surprise if ETH will almost beat BTC top 1 position in the future