"So let’s talk both about whether BitCoin is a bubble and whether it’s a good thing — in part to make sure that we don’t confuse these questions with each other."Modern Keynesian economists believe that a modest amount of inflation is beneficial to the economy since it spurs spending instead of holding. In this light, Bitcoin would certainly not be considered "a good thing" as a currency replacement. Bitcoin has a long term capped supply of 21,000,000 coins. Over the last ~100 years the largest central banks have moved away from supply capped currencies. In fact, the world's reserve currency has lost 98% of its purchasing power since 1900. This means that people are forced to seek a replacement value-store that will keep their assets safe over time. Most Americans use the stock market and real estate to attempt to do this, but both are a gamble for obvious reasons. This brings us to Bitcoin.
Bitcoin adoption is not in any way driven by the "right" economic model. That is to say that individual consumers are generally rational towards their own goals, not towards macro economic goals. In the case of Bitcoin, their goal is, among other things, to store value, and not accept inflation of their currency (as some economists believe would be beneficial). This leads to a clear conclusion: Adoption of Bitcoin is unhindered by its deflationary function. In fact, the deflationary function makes it appealing for people who are looking for a safe haven from inflation. While a deflationary currency may or may not be stimulating to the economy on a macro scale, that is a totally separate and somewhat irrelevant discussion at this point to consumer Bitcoin adoption.