What's the problem that cryptocurrency is supposed to solve? That governments can screw up money management? Well so can the miners who control the cryptocurrency, and not only are they less accountable but their motivation is keeping the value high, not keeping the economy healthy.
It is that people don't want to trust banks? Well now you have to trust the crypto exchange and all the apps on your computer.
I think that, at its core, Bitcoin was intended as an experiment. I wasn't actually there, and I claim no firsthand knowledge, but it seems to me that the intent was to implement some interesting ideas that had never really been tried before, or had never been combined in that way before, to see if currency could be (a) virtual, and (b) decentralized. It was really far out in left field at the time, and it brought forth some ideas that were genuinely novel. It was almost certainly far more successful than its creator(s) ever thought it would be.
That's not to say that Bitcoin is without problems. I could rattle off a long list of issues, and many of those issues are what makes it unsuitable as an actual unit of currency. It is successful in spite of these flaws.
What's really interesting, though, is the general field of cryptocurrency that it spawned. Among the countless crypto copycats, there are some genuinely interesting attempts at reinventing cryptocurrency to solve one or two or many of the fundamental flaws in Bitcoin. Some with more success than others. And those attempts will continue, until someone hits on the right formula -- something that provides genuine utility. It's not really about "Bitcoin" anymore -- that's just the oldest and most well-known version. It's about what comes next that is really interesting.
And by spawning all of those efforts, Bitcoin was clearly a successful experiment.