I also want to raise the possibility that there are, in the very long term, "virtue effects" in economics- for instance that widespread corrupt accounting will eventually create bad long term consequences as a sort of obverse effect from the virtue-based boost double-entry book-keeping gave to the heyday of Venice. I suggest that when the financial scene starts reminding you of Sodomand Gomorrah, you should fear practical consequences even if you like to participate in what is going on.

If you can get good at destroying your own wrong ideas, that is a great gift.

Obviously, consideration of costs is key, including opportunity costs. Of course capital isn't free. It's easy to figure out your cost of borrowing, but theorists went bonkers on the cost of equity capital. They say that if you're generating a 100% return on capital, then you shouldn't invest in something that generates an 80% return on capital. It's crazy.

Mimicking the herd invites regression to the mean.

Kellogg's and Campbell's moats have also shrunk due to the increased buying power of supermarkets and companies like Wal-Mart. The muscle power of Wal-Mart and Costco has increased dramatically.

Step by step you get ahead, but rarely in fast spurts.

It is way less certain to be a wonderful business in the future. The threat is alternative mediums of information. Every newspaper is scrambling to parlay their existing advantage into dominance on the Internet. But it is way less sure [that this will occur] than the certainty 20 years ago that the basic business would grow steadily, so there's more downside risk. The perfectly fabulous economics of this business could become grievously impaired.