ETH has shown over a long time that it is quite volatile, ETH can be invested for trading as well as for the long term because ETH can grow very much in a short time.
There is something we can't escape from volatility, in fact, we live this thing since the day that ETH is created. But if we look at its fluctuating rate compared to the other altcoins, you can find that ETH didn't have that much volatility. If I have to invest Ethereum, I'll consider this as a long term investment rather than of short-term one because you can just make money if you can manage to hold it for a long time.
I think the ethereum market is stronger than the other assets. maybe a fast chart movement occurs because of a sudden drop in the price of bitcoin. of course, it not only affects ethereum but also other assets. I agree with you, ethereum will be better for the long term than for a daily trade.