Bitcoin is only general AI for now.
Smart contracts are single-minded even for (AI)'s; while some may have very advanced pattern recognition or legal thinking modules the "only" thing they care about is performing their contractual function. They might know major secrets, but if they are written to be quiet about certain aspects, they will remain quiet no matter what.
It can reach the point where your own pc, house, car or phone might be hired by a contract to check certain information. A high tech "wire tap" investigation of sorts built into the agreement of the contract. This would occur when the contract has started to think one of the parts is doing advanced cheating that it cannot detect online.
With respect to strong AI, Nick Szabo(as you can read in his blogs) is very close to the problem, and that's the issue. Like any good engineer/scientist, he sees problems everywhere. Yes, there are many problems before we get to strong AI. That's not news. There were many problems to resolve before people could pay a small sum of money and let a giant metal tube take them through the air to a destination halfway round the world without killing them - but those problems got resolved, one by one. Many problems do not amount to an impossibility, only a damn hard problem (which we knew strong AI was anyway).
You do see a lot of it in books and movies, some very well thought. Referring back to Nicks blogs, his other assertion, that the concept of the singularity is mostly a fantasy, Nick's main argument is that the singularity will only last "for a time", and that it will turn into a classic S-curve. He waves Feynman's name around as supporting evidence, but does not address the fact that intelligence (and artificial intelligence in particular) is not subject to the Malthusian laws which have caused other phenomena to follow S-curves. Yes, we only have access to so many particles, but the whole point of exponential AI is figuring out better ways to use the same number of particles. There may be a theoretical limit to how efficiently we can use those particles, but even so there are a lot of particles, and if we can manufacture even just human-equivalent computing matter in factories, that's already enough to achieve a singularity.