I didn't mean to imply that it was. I don't think I said that, but I can see how it might be interpreted that way. Sure, it's a (terrible) financial system for legal transactions as well. (Terrible defined as slow, expensive, and volatile - pick any 3.)
Cash works for things that are grey enough that Visa and Mastercard (or more accurately, banks, won't get involved in.) So yeah, there's a niche for bitcoin use there as well (although I'd argue that if your business requires something like bitcoin, or cash, to succeed, then it's not much of a business...)
Of course, sure, if you're anti-establishment then it's a good option as well. Again so is cash, or apparently gold.
The traditional financial system is formed of many layers. At a high level, it is: central banks, commercial banks, then card processors.
You have to change your view to see Bitcoin as the settlement layer of this new anti-establishment currency, similar to how central banks settle today. That doesn't need to be fast, it needs to be secure.
Bitcoin is pretty fast in settling relatively speaking, at least compared to other currencies.[1] It's important to look at the amount of value (electricity, power, money) that backs the block, instead of the raw block speed. People mistakenly compare block-time - look at Litecoin, it doesn’t matter if it has 4x faster blocks when 4 Litecoin blocks are worth many many times less than one Bitcoin block. The cost to reverse (51% attack) a transaction is much lower.
If you agree with that view, then the Lightning Network[2] can be a promising solution to the slow and expensive argument. It isn't a 1:1 replacement to Bitcoin (someone else will likely need custody your coins if this scales to a global level), but it does solve the problem.
As for the volatility, I think it's entirely expected to have extreme volatility as a currency is monetizing[3]. There's no real way for it to get from $0 to $2T of market cap in less than two decades (and perhaps go toward $20T) without large price appreciation and subsequent busts. Look at Apple stock as comparison. And it's not a fair comparison, because a stock has an underlying revenue stream that puts an implicit floor and ceiling to its price, whereas a monetary asset like Bitcoin doesn't.
In essence, I believe it's premature to declare it "already failed" at being a currency. Although I agree that the signs of becoming a currency aren't strong.
1 - https://medium.com/@nic__carter/its-the-settlement-assurance... 2 - https://www.lynalden.com/lightning-network/ 3 - https://www.2minutebitcoin.org/blog/i-love-bitcoins-volatili...
Of course, you would still need to be able to either pay for stuff with Bitcoin or convert it into fiat currency to realize the claimed gains.
So if it went from $100k to $10k in the next year, stayed at $10k for a few years and then trended toward $0. I think I would define that as failure.
What do you think then?
I guess that happens when there are no longer fools willing to play. That could happen tomorrow, or in 10 years.
It probably doesn't go to zero (it still has value other than speculation) but getting price stability would actually make it more successful (as a currency) than it is now.
I could imagine it happening over the course of years. But the question then is - what would it take to change the public's minds?
Usually this happens when the money runs out - when it's no longer possible to find the next "greater fool".
That might take a while - there's a LOT of money in the world, and a lot of greedy people willing to be convinced that there's gold in them thar hills.
It has already failed at the goal of being a currency. It lacks the attributes of a good currency, and shows no sign of gaining them.
It has already succeeded as a financial system for illegal transactions. That success won't go away, until bitcoin / $ exchanges go away. (Which will likely be never.)
Speaking of crypto in general, it is successful in parting fools from their money. Between the inevitable boom / bust investment cycle, and the high-profile exchange scams, there is no lack of bigger-fools willing to lose money.
It is successful at illegal transactions because its physically safer than cash. It is successful at speculation because people are greedy. Neither of those conditions are changing anytime soon.