The following part of it self-discredits the whole memo.
Lately, I’ve been repeating a quote I attribute to Warren Buffett: “When investors forget that corporate profits grow about 7% per year they tend to get into trouble.” What this means is that if corporate profits grow at 7% a year and stocks (which represent a share in corporate profits) appreciate at 20% a year for a while, eventually stocks will be so highly priced relative to their earnings that they’ll be risky. (I recently asked Warren for a source on the quote, and he told me he never said it. But I think it’s great, so I keep using it.)