You've missed speculation and gambling. Not to say it's a great use case but it's the biggest. Most people buy them because the number goes up, not to buy drugs etc. Which is perhaps a bad idea but not actually illegal.
Yes, I think this is the 99% use case. A strong indication of this is the fact that they are very volatile and all tend to move in tandem.
Normal, real G7 currencies moving full percentage points in a day is a big deal, 10% moves in a day are very rare, 20% is a once in a lifetime event.
You would expect the different cryptocurrencies to move in different directions and speeds depending on their relative prospects. Instead you have these crazy days where they all go up 5-10% or down 5-10%, over and over. I hold about 8 of them in my wallet and yet still see pretty normal 10% daily moves.
The closest thing this reminds me to is trading bank stocks in 07-08 when everyone was gambling on which would go out of business.
A currency that regularly moves this violently is not an inflation hedge as a savings instrument store of value, nor is it a useful medium of exchange as how do you agree on a price when its moving by the hour.
It is clearly not a unit of measure either given that all the crypto apps report the value of your portfolio in.. fiat. Even these crypto give aways as exchange sign up bonuses or conference prizes are always worded as "$5 of ETH" or "$500 of bitcoin", haha.
A currency that can move 5% on a Sunday afternoon (again) because of an Elon Musk tweet (again) is not something to be taken too seriously (still).
Consider that by comparison, when the UK voted to Brexit, which was not what polls indicated.. a huge economic change with profound generational implications for both GBP & EUR ... GBP-EUR only moved 7%!!
