If Ethereum is a utility platform and the value of its coin rises, how can it continue to be used as a utility when its used as a store of value?
Most people that buy Ethereum aren't using it, they're trading.
What you say about Ethereum applys to all other coins to an even greater degree. 94% of the ICO's conducted in the last year were done on the Ethereum Platform. Of all the coins it has a stronger case of real world use than any other Coin, even Bitcoin. A lot of other coins claim to be technically better but none of them have a proven use case better than Ethereum. Ethereum remains the base currency for all those that invest in the development of Blockchain.