nine,
If you truly feel free, you are. It's really the mind that keeps us in bondage.
I probably wasn't clear when I wrote that "widely traded financial instruments are essentially 'random walks'...". I wanted to convey that trying to perceive patterns in a time series that is 95% a random walk, one can easily be led astray. We tend to overestimate our ability to discern meaningful patterns, like "seeing elephants in the clouds". I can't tell you how much "technical analysis" I've seen over the years that was either too vague to be useful, or just plain made wrong predictions.
As I've said many times, there is a small deterministic component in financial series', and that's what traders exploit to make profits. Statistical methods such as statistical arbitrage are an attempt to formalize those efforts.
As for my qualifications, I have an advanced degree in physics, and I've worked as both a scientist and as a software engineer for over 30 years. I've studied time series analysis in some detail, and I've made a serious effort to apply these methods to trading, which appears to be bearing fruit. I guess that gives me some right to express an opinion on a trading forum.
With regard to your statement, "What I do know for sure of statistics is that we tend to underestimate our ignorance", I would say that statistics, when properly applied, helps to keep us honest about our level of ignorance. We can quantify our uncertainty. That said, all models are a simplification of reality, and so are not absolute truth. They can be useful, nevertheless.