Well you've flipped now to discussing the definition of useful, no?
First, gold is plenty useful outside value store: only ~30% of new gold per year is used for investment (this is per GS in 2015, I believe, and this is unlikely to have changed significantly one way or the other, pls feel free to correct me). The majority of remaining is used in mainly in jewelry & electronics (again per same source).
Second, on its way to providing for the point above, it employs hundreds of thousands of people full time that take that money to spend, save, invest aka. it works in the economy.
I'm not saying that bitcoin can't function like this or some similar way in the future, but it's a fact that it doesn't right now, and per this criteria I would say it's both more wasteful & less useful than gold. Bitcoin is simply plugged into your outlet right now and quite literally wasting energy unless you're using it to heat your home. That people have assigned value to the record of energy being spent is a separate phenomenon IMO.
