Well I have to say as someone who was out of active investing for about a decade, the way the markets have changed is a little shocking. If the market was stacked against the retail investor before, it's 10-fold worse than it was before.
Social media is, in particular, a curse--disinformation and distortion is spread almost instantaneously, and retail investors are particularly vulnerable to this sort of thing. Automated trading attenuates gains almost instantly and exacerbates moves to the downside.
Add that together with the absolutely toxic political environment and the fact that government has been sticking its nose into places that it shouldn't and we've got a mess. I've always thought that the market mainly exists as a wealth transfer mechanism from poorly informed retail investors to the wealthy, but I think we've arrived at the point where it's clear that your average poorly informed retail investor should stay out of biotech and the other more volatile sectors of the market.
I also think that, except in rare instances, fundamentals and data no longer matter that much, as they will quickly be buried under a pile of garbage.
That said, you can throw the efficient market hypothesis out the window, and that creates a ton of opportunity. I also think that to make money you have to be willing to play the long and short sides equally--I was always 80% long, 20% short, but no longer.
