If you want to play that game you have to compete against large firms that have buildings full of people looking into the fundamentals of the companies. Or you need some other informational advantage.
Otherwise you are almost certainly buying correctly-valued stocks. That's not value investing, but you can do something else that is useful, like buy an index.
For one thing, there are lots of companies I can buy into that Warren Buffet can't, because he can't take a meaningful (to him) position, because he would end up owning the entire company. And even that may not be enough to be meaningful to him.
I suspect this phenomenon also exists for firms and institutions much smaller than Buffet. It may not be that they would own the whole company, but simply that they would own too much of it and/or move the price on their own.
For another thing, lots of investors are irrational. They follow fads. There are certainly opportunities for contrarians.
Value stocks have underperformed in the last 12 yrs, but these things tend to follow cycles, so I'm guessing they will have a comeback. Here is an article about that: https://www.wsj.com/articles/the-agony-of-hope-postponed-by-...
> you can do something else that is useful, like buy an index
That is precisely not useful in terms of efficient price discovery, though it may be "useful" to the individual investor who has better things to do with his or her time. That is one kind of behavior that causes inefficient markets that careful investors can then exploit.
It's what the vast majority of people and businesses do with their money. Only a small percentage are investing in risky trades. And the ones that do that have plenty of money to spare and are well aware of the risk models.
The vast majority of people invest in founds that deals with short-term gambling. Heard of LTCM?
I really doubt that.
What does that have to do with the average investor?