Answer by Alex Lightman:
No and yes. He is making this optimistic assertion for the same reason he says many things: to keep people interested in investing, even when, like now, the market has been plumped up and pumped up by a tidal wave of money from years of Quantitative Easing. If there was a stock that Warren Buffet thought or knew was as undervalued as stocks he bought in the '50s that went up 10x or more, he would have already purchased them.
It's worth pointing out that part of the reason that Warren Buffet does well is that there are, by my estimate, over 300,000 people who seek to match Buffet's portfolio and buy what he buys and sell what he sells. I call them Buffet Mirrors. However, note that they always buy after Buffet buys, and sell after Buffet sells. This is a huge advantage to Buffet.
Perhaps it is true that he could find that he could find stocks that are undervalued, but a part of the reason they are undervalued is that he has a great reputation, and his act of purchasing these stocks imbues them with greater attractiveness then they had prior to Buffet's purchase, so, while the stocks may go up, it's not for exactly the same Graham-ish fundamental reasons that the stocks in the '50s went up.
Edit: A commenter misread this. I am not saying I am a better investor than Buffet. I am not saying he is a speculator. As with everyone on Quora, I am entitled to express an opinion on a question that is a combination of both speculation on what someone is thinking and what facts are relevant.
When someone says "No and yes", and gives reasons, you are free to give your own answer that is "no" or "yes".
I am of the opinion that part of the reason for Buffet's success is factors beyond Graham fundamentals, and I think people are naive if they don't think Buffet uses the investor equivalent of 'PsyOps' or Psychological Operations.
If people think there are no bargains, they invest less. It's in the interests of every investor who has big holdings to get more investors to make more investments.
I recently finished reading several books that show how the richest are benefiting disproportionately from the US economy, such as The Second Machine Age and Race Against The Machine.
The potential exists to have robots and AI replace 100 million jobs out of 139 million jobs. While I have no doubt that the billionaires will get richer, I also have no doubt that the bottom 50 to 70% will not necessarily have the same investment opportunities as billionaires.
For instance, individuals can't acquire 100% of companies with a billion dollar or more in earnings. Buffet can.
So please don't tell me to read books about Buffet, as if he is simply following the guidelines of books that everyone can read and act on, as if the playing field is as level in 2015 as it was in 1955. It isn't.