all its doing is creating rules based on previous patterns it spots (neural networks).
if the futures patterns don't match its worthless (which is what happens in markets).
I listened to the music a while back, and it seems impressive until you realize its just a rehash of other peoples previously original work mixed up with some modifications, like a rapper sampling other peoples music. It is not creating original music, its following rules it has created by sampling original music.
But what you described is EXACTLY what humans do when we write music. There's a famous quote: "Good artists copy, great artists steal". A more accurate rewording of this would be "All artists steal". When a person composes music, it is a product of their musical experience. They aren't just throwing random notes onto a sheet. Every musical composition is a rehash of music that the composer has heard before. The best example of this is basically every blues song ever written. They all follow one of a couple possible chord structures, they generally use the pentatonic scale for melodies, and even the lyrics tend to be of relatively similar subjects most of the time. In short, musical compositions come from people's brains, and people's brains are formed by their experiences. Training a neural network on people's musical compositions and teaching it to write music itself is basically a simplified simulation of this.
To say that the neural network is creating "rules" is a bit of an oversimplification. They learn patterns, which you could argue are rules, but by that same argument everything is rule-based. Back to the blues music example, you could say that composing blues is rule-based. That actually wouldn't be terribly inaccurate. Like I said, you choose a chord progression and follow it... and then you take a bunch of short riffs from other blues songs and combine them into a melody... BAM, you have an original blues composition.
I would argue that the vast majority of high level tasks that human brains can perform can be boiled down to pattern recognition. Vision is pattern recognition - we recognize patterns in the information being sent through our optic nerve, and map those patterns to higher level neurological structures that represent things like "cat", "dog", "Obama", etc. Our brains receive information from our ears that can be mapped to higher level structures that correlate with higher level abstract representations of what we are hearing. We may classify a sound as a voice, and then at an even higher level, classify it as Morgan Freeman's voice (for example). And you keep extrapolating up to hear patterns that represent words, and patterns of words that represent sentences, and patterns of sentences that represent thoughts. Every step is just a pattern recognition task, that takes something like raw sound information represented by the binary behavior of neurons (they either fire, or don't fire), and extrapolates a high level coherent thought out of it.
Basically, human brains are simple. Or rather, the components of a human brain are simple. The way they interact with each other is obviously wildly complicated... but brains are basically just a bunch of binary units... a bunch of neurons that are connected to each other, but all they do is fire, or don't fire. It's how they are wired up that allows us to perform high level tasks like what I mentioned in the previous paragraph. There is no reason that computers can't theoretically simulate many of these tasks.
Sorry for the giant monolithic response haha... I just really enjoy this topic. I find it super fascinating and exciting!