Well what does?
More people using it and interested in it? Doesn't define success.
More merchants accepting it? Doesn't define success.
More governments paying attention to it? Doesn't define success.
What on earth would define success? It's like nothing is ever enough for you people.
Kinda reminds me of all the people confidently predicting the demise of Google before the "ridiculously overvalued" IPO. There was even an entire web site devoted to it called fuckedgoogle.com. Needless to say, it went out of business waiting for Google to go out of business.
It existing and being available for those who truly need decentralized money. It's a bit like saying the success of Tor is when X% of the internet's traffic is over Tor. No, the value of Tor comes from just existing and working when it is needed. Likewise Bitcoin provides something very different from fiat money, and success for bitcoin is retaining those properties and availability as needed.
There literally is no way to get an amount of "active wallets". First, what constitutes active? Second, what defines a wallet? For me, one address is a specific wallet, and I use an HD for different things.
If you look at the bottom of [1], you'll see it's pretty hard to get just a "volume" metric as well.
It's worse. Continuous deflation (increasing real value) is a very undesirable characteristic for a currency as it dis-incentivizes the actual use of said currency. Why spend money on anything not absolutely essential if the money itself will appreciate in value more than any investment you can make with it, and with no risk?
It might be okay for domain specific uses but for general purpose currency use it's awful. If the world ran on Bitcoin as presently implemented we would enter a permanent depression.
(Too much inflation is also really bad, but Bitcoin definitely doesn't have that problem.)
I'm very bullish on the idea of cryptocurrencies and the technology of block chains, but I regard Bitcoin as kind of a proof of concept toy. It's version 0.1 alpha of something that might someday change the world.
2008: Satoshi posts a paper to mailing list, nearly everyone declares the idea non-workable.
2009-2010: Satoshi releases software, no one cares. People throw away wallets with mined coins.
2011: A 8-month decline after the first speculative bubble.
2012: "Nothing" really happens price-/news-wise, only minor bubble from $5 to $15 to $10.
2013-2014: A year-long price decline in '14 after mtgox fallout, after the second and third big Bitcoin bubbles in '13.
2015-2016: Price went up from $250 to $1000 among the news talking how "Bitcoin is not cool, DLTs/R3/private blockchains are more interesting".
2017: Price continued from $1000 to $4000. Bitcoin is now finally entering a "trough of disillusionment".