Here's an interesting thought. It's pretty well known that there's a lot of luck in the markets - even someone who does all the research in the world can have a terrible run of luck (the company they invest in is hiding its losses, a new technology develops which supersedes an old one, etc) and even a complete idiot can blindly invest in a stock that happens to quadruple in the course of a year. When the market is volatile and has long runs like the ones we've seen recently this is doubly true.
Given this, it's not obvious that someone who does well in the markets actually has any skill (though they might) and equally someone very skilled can lose money. Even Warren Buffett has bad years.
So the following scenario is really very plausible: someone with zero, or a very small amount of skill, begins investing. They're not 'blindly' investing because they're doing research, reading company accounts, using tech analysis, or whatever your favorite heuristic is for choosing what stocks to buy. But they don't really understand the markets - all their effort doesn't hurt them, but it's not helping them either.
Wouldn't it be quite possible for such an investor to lose money for 18 months, and then make money for 18 months afterward. Not because they got any more skilled, but just because they were unlucky to begin with and lucky afterward.
Of course, such an investor would probably *think* that they were getting more skilled, because all they see is that they used to be losing money, and now they're making it. They have no idea that they might suddenly start losing money again in the next 18 months (and if they did, they'd surely have a good explanation... "just bad luck" or "unpredictable market moves" or "unforeseeable liquidity crisis").
Now, wouldn't such an investor, if they decided to post about their investing on a popular internet forum, make a post very much like this one:
I will categorically tell you now, you WILL lose more than you make for at least a year (even if the markets aren't as mad as they have been).
It took me 18 months of frustration (I've gone through 5 keyboards, seriously), research and bloody hard work to finally get it. I'm now making a very good return.
As I said - just a thought.