[lottin]

You're quite right that neither fiat money nor bitcoin have intrinsic value, though they both have exchange value (i.e. market value). This means there must be a demand that prevents the market value from falling to zero. In the case of fiat currency, the public demands fiat currency for transaction purposes and to pay taxes. In the case of bitcoin, the demand for transaction purposes is anecdotal, almost nonexistent. So the demand for bitcoin is almost entirely speculative. (There's no other possibility as far as I know, given no intrinsic value.) In other words, people demand bitcoin because they expect that the price of bitcoin will go up. Such a demand can be sustained as long as people continue to have the same expectations. When (or if) these expectations change, the demand can evaporate quite quickly, and the price will collapse dramatically as a result. So bitcoin is not backed by math. It's backed by a speculative demand.

[superfist]

Yes, but even speculative demand consists of many levels of speculation. For example, I speculate (based on history) that the world will always consist of corrupt governments printing money like crazy, so "digital gold" will be much better for their citizens than what they have to offer. How reasonable is my speculation? Other people speculate that Bitcoin will double in value, while others speculate it will increase tenfold. I believe their speculation has less merit than mine (at least, that's how I see it). I also speculate that a programmable, permissionless money system, similar to SWIFT, is a very interesting idea that opens up many research avenues and there is some non zero value in it. Another example: How many gatekeepers do you think someone in a poor country has to pass through to transfer dollars internationally using their bank account? You really think there is no value in avoiding all those proxies that charge you high fees? So yes, there is a pyramid of speculations, but some of those speculations are much more reasonable than others.

[lottin]

Speculation is always based on future price expectations. Whether such expectations are justified is a matter of debate of course. Personally I don't find any of the rationales convincing, quite the opposite. But, look, we already have examples of irrational behaviour such as in the case of lotteries. In principle, no rational person should buy a lottery ticket, since the expected value of a lottery ticket is negative. Yet many people buy lottery tickets. The world is full of gullible people who are willing to believe that they can get rich for free.