As a follow up, I did dump my SPY puts at 140.40 this morning for a small gain. Didn't like the strength in AAPL (and the overall stickiness of the NAZ) as far as the short side went.
As far as addressing your major points:
https://forum.mrmoneymustache.com/investor-alley/efficient-markets-rip/
This is more of a niggling at some of the finer nuances of the efficient market theory than undermining the conclusion that the stock prices are essentially random (though as an aggregate net positive returns) and that people without extra information can't outperform the stock market above chance.
The first two points address concerns that a truly efficient market with perfectly rational people shouldn't have generated the massive collapse. Fair. A common shortcoming of classical economics is that it assumes all participants are perfectly rational. So yes, this collapse indicates that EMH isn't a perfect explanation of market behavior. Practically though, this doesn't undermine the conclusion that market behavior is unpredictable and cannot be profited on above chance without additional information. Are changes in stock prices by irrational investors predictable? Theoretically, yes. Practically it has yet to be demonstrated.
"If the markets are efficient, then no one can [devise an effective strategy certain to] beat the market in the long run; an apparent long-term success can happen by pure chance only."
That sentence doesn't even make sense, so I added the bracketed portion. If you had monkeys randomly invest in the market, after 20 years, around 1 in a million would be expected to have beaten the market every single year by chance alone. Fair premise. Let's move on.
"However, argues Buffett, if a substantial share of these long-term winners belong to a group of value investing adherents, and they operate independently of each other then their success is more than a lottery win; it is a triumph of the right strategy."
That's not a valid argument. Let me make a valid argument that WOULD undermine the assertion that there's no strategy that will beat the market above chance:
"However, argues chucklesmcgee, if
a substantial share of these long-term winners belong to a group of value investing adherents value investing adherents are over-represented in successful long-term investors relative to investors as a whole across multiple time spans, and they operate independently of each other then there's evidence that a strategy exists which delivers above-chance returns."
For the sake of argument we also need to assume that value-investing adherents (VIAs) all can be identified as such and all actually work on some definable and uniform set of rules. Just because a lot of the successful investors are VIAs doesn't mean VIA is a successful strategy. Is every VIA a successful investor? Does every VIA get above average returns? Has no VIA gotten below average returns? And really, the bottom line question: On average, do VIAs outperform the market average in the long-run?
Buffett's book is not empirically rigorous at all and doesn't advance his theory. He basically picks out 9 individuals he claims are VIAs who had returns well above the market average, for portfolios starting at different times, ranging from 12-28 years. Well that doesn't prove jack squat. These are numbers entirely within chance. Yeah, I bet 9 people over 6'0" also outperformed the market over a similar period, did being tall cause them to be great stock pickers?
So I suppose whether or not the market is truly efficient or not is one for academic contention. But my conclusion stands. There's no definable strategy that will give an ordinary investor sitting at home an above-average chance of beating the market or predicting the market in advance. My contentions that there's no one out there capable of making stock predictions better than chance or defining a strategy which gives better than chance returns stand. This world of market prediction speaks like pseudoscience and avoids making testable claims to every truly prove they're wrong.