It seems like traders are certainly acting selfishly if you look at it in a big picture context - they are sucking out value for themselves rather than contributing to the overall value of the cryptocurrency network. A day Trader only wins if they successfully take profits at some point.
But that doesn't mean it is unethical - just that it isn't in the best interests of cryptocurrency.
Ray Dalio, legendary investor and founder of Blackwater, offered a few insights about cryptocurrency during an interview w/ Tim Ferriss that dropped a few days ago. He basically suggests that you can measure the long-term value of a blockchain by the amount of HODLers on it - the more, the better. At least that's what I took from it.
Edit: and I'll admit that I could be wrong about all of this because I am not an economist...