The assumption of a bubble is generally based on Paul Krugman's neo-keynesian fantasy world where people don't spend deflationary currencies. But people do - when their need for something in the immediate present surpasses the potential future value of the currency they will spend, and this is why we see record numbers of merchants signing up with bitpay. They're not signing up based on speculation, they're signing up because regular customers are emailing them and requesting that they accept bitcoins.

We don't need to pop the bitcoin bubble, we need to pop the fantasy bubble in these peoples' heads that convince them that bitcoin is a fad based on neo-keynesian "spend spend spend" bullshit. Bitcoin (or at least cryptocurrencies in general) are here to stay. And yes, it can be both a deflationary store of value and a currency. Perhaps it doesn't encourage unsustainable levels of consumption like the USD - the dollar is like a hot potato. I get rid of USD as quick as I can, either into deflationary alternatives or goods/services that I can't yet buy with deflationary decentralized currencies.