Why?? Answer is very simple. Ethereum is a hyped coin and when the hype settles/gone then it's value is also gone.
Why i don't invest in Ethereum is that because of its infinite coins to be mined which is a major drawback according to my strategy.
Infinite?? Isn't it going to switchto POS soon? By switching to POS you will no longer be able to mine any more Ethers.