> If crypto is money, can I quickly, efficiently and without huge fees: Spend it at Amazon? My grocery store? My corner deli? Pay my rent? Pay my employees? Pay for dinner?
I've seen people do all of these things, but in every case it depended on cryptocurrency hobbyists happening to be on the other side of the transaction, or on informal exchanges (and the trend may be that it's getting less common, not more). So it seems like the answer is "maybe, but not reliably and routinely".
In this regard, cryptocurrencies might be more like commodities, collectibles, historic currencies, or foreign currencies (that are pretty much always still foreign, no matter where you travel).
> If crypto is a store of value can I trust it will hold value in any sane, non-Venezuelan way, over any reasonable time period?
Nope; in this regard, cryptocurrencies might be more like commodities or collectibles. "Not all plates go up in value; some go down." (National currencies can also be volatile, but most are dramatically more stable than cryptocurrencies.)
You could try to hold a stablecoin, but it's not clear that the backer will be able to maintain the peg (or even that the backer itself believes that it can maintain the peg!). Futures traders might be able to force the issue unexpectedly.
> If not, doesn't it default to a cool technology with no current useful application??
Most of the financial applications aren't currently routinely useful to most people. Although some people are optimistic that this is just a temporary bug or a matter of growing pains, I'm concerned that there are pretty strong scaling and sustainability problems with cryptocurrencies, so it might not be easy to fix this.