Is it immutable? Forks, 51% attacks, bugs. It it only immutable until consensus decides it isn't immutable, right? If something is immutable, but can be made immutable, is it ever really immutable?
The context I think they are proposing blockchain to be useful is in verifiable public information. For information to be verified or analyzed the blockchain can verify the source even offline.
It's still extremely useful as currency as well, though, precisely because it actually is digital currency, and allows direct person-to-person transactions via the internet without requiring a proprietary middleman. The previous commenter's complaint about how it doesn't solve anything if you get scammed is a bit off-target, because dealing with frauds and scams isn't a feature inherent in the currency itself -- it applies equally to any payment solution, especially cash and checks -- and is something we deal with via the legal system regardless of how funds are transferred.
Simple: demand.
The value of Crypto products is based on scarcity dictated by the computationally intensive nature of certain algorithms, and on people believing those products have value.
You mean math?
1. Speculation / belief
2. Approx 10x less influential is trade, most currency transactions both by volume and by value are in speculation which is underpinned and driven by beliefs in a particular currency. Some estimates put trading as low as 2.5% of all forex. Trading does impact the price of a currency, but in miniscule proportions to speculation
3. We can fairly confidently say tax collection is a lower influence than trade because of so many examples (and extraordinarily rare counter examples) but I don’t know of any reasonable way to quantify how much less the effect is. The threat of incarceration and / or asset seizure drives demand for currency which influences its value.
Places like Argentina are fascinating (said while acknowledging the extreme hardship being placed on people who have to use Argentinian currency!). In recent history all of the above have had visible influence on their currency along with pegging / dollarization which attempts to introduce a control on all the above factors with various degrees of success.
Apparently Monero has some weaknesses [0]. Time will tell how effective it is once the mask of parallel construction slips.