You can use logic to determine markets are random walk/ unpredictable. Markets can be broken down to individual players. Each player only has 3 possible moves sell-buy-hold. All players play to make profit. The players only choice is follow trend, be contrarian or neutral. Any given day more players join or leave. The only time anything is predictable is when you get a volatility spike or dip and volatility always revert to mean. This usually happens on significant news. Most experienced traders know this from trading everyday.
Or you can also just use Occam's Razor. If markets were predictable then everyone would be doing it. If everyone did it there would not be a market.
Since I first commented in your thread a month ago I tried to Google "neural networks" and market prediction. Seems like this was tried for a while in late 80's wary 90s but no big firms believe in this method. The big trading firms have all the money to hire the best scientists & mathematicians in the world. If they don't believe in it then it probably doesn't work. Most of the "quants" in Wall Street are hired to calculate statistical probabilities. They make trading decisions based on long term statistical strategies like "statistical arbitrage" or they try to determine if the derivatives are correctly priced or not using concepts from Game theory, Kelly criterion gambling, etc.. This is not the same as price prediction! I only see some fly-by-night amateur website or youtube channel claiming to be able to predict price using "neural networks". And from what I've seen it's just some lame technical indicator.
What I learned about "neural networks" is that its mainly used to teach computers to recognize patterns. Things that humans have no problem doing like speech recognition. Seems to me like you are misapplying "neural networks" here. First you claim that computers are better at recognizing patterns than humans. This first point is already debatable. Second you argue that there are patterns in market prices. This is the Technical Analysis argument. There might be some patterns occurring some of the time but its not consistent enough to create a complete trading system. And since most trading firms are moving away from technical analysis and towards quantitative analysts, it should tell you that quantitative trading is far more profitable than technical trading. Fundamental analysis is still dominant for the "investing" world though.
If you Googled neural networks then you should have found the numerous studies where they were used for stock price prediction successfully. Neural networks were not used much at all in the 80s. They were first created in 1943 and then barely used again until the 1990s/2000s. But this is irrelevant.
You are not the first person to make the statement "If price prediction were possible, everyone would be doing it". I'm sorry to be a dick here but this is just an extremely stupid statement. There are tons of things that are possible that not everybody is doing. One project that I was thinking of doing at one point was writing a mobile app that could recognize and identify bird calls (which there is a high demand for actually, and does not yet exist). I didn't follow through because I didn't have the data that would be required, but it is absolutely 100% doable. If we can recognize human speech and we can recognize music then we can definitely recognize bird calls. The statement that everybody would be doing this makes the false assumption that everybody knows how to do this and has the resources to do so. That is obviously false.
Furthermore, as someone who has a much better understanding of neural networks and their uses than you do, I can assure you that they do things that humans can't even come close to doing. Yes, they are used for speech recognition. They are used for computer vision as well. In fact, the first time I created a neural network was to recognize hand-written digits. It performed better than a human. Neural networks can solve the traveling sales person problem, which humans are obviously very bad at. They can be used for image compression. They can be used for countless other applications. As I've mentioned, commodity price prediction is also one of the standard uses of neural networks. This isn't something I'm inventing. However, I'm trying to be innovative in the manner in which I am applying neural networks. This is far from a "misapplication".
You argue that there are no consistent patterns in price fluctuations. The mere existence of my project 100% proves this wrong. My software finds patterns in the data, and these are patterns that no human could ever find. You are basing your arguments and assumptions here on what you see and believe as a human looking at an insurmountable amount of data. If my software was not finding consistent patterns, it would not be able to attain the average error figures that it does.
It seems like you are just dismissive of neural networks because you don't understand them. It is one thing to be a bit skeptical, but don't judge something unless you understand it. I can tell that your "research" of neural networks was extremely limited, so I recommend actually learning a bit about them if you are going to try to make an argument against their effectiveness in this application.