(The titular insight seems pretty deep, thanks for sharing this)
This is not exactly central to your main argument, but I think it’s worth pointing out, since this is something I see even economists I really respect like Scott Sumner being imprecise about: Even if markets are efficient (and I agree they pretty much are!), then prices can still be predictable.
This is the standard view in academic asset pricing theory. The trick is that: under the EMH, risk-adjusted returns must follow a random walk, not that returns themselves must follow a random walk. I have an essay explaining this in more detail for the curious.