> It's real, measurable economic activity on a massive scale.
What economic activity? It is people speculating. Nobody is using bitcoin for buying coffee or sending micropayments to websites. Nobody is using it as a "store of value", despite what the shysters say. It is just people buying and selling a meaningless ticker symbol hoping to get rich and buy some island in the south pacific (using fiat, I might add).
With bitcoin, you might as well just throw away the technology behind it and just trade on the BTC ticker instead. I mean, that is almost what is happening given all the trades on any given exchange are off-chain transactions happening in a centralized exchange-owned database. There is no rumbling of miners recording every trade. The only people doing cross-trade are people trying to arbitrage away the price difference between exchanges.