Psychologists led by Baruch Fischhoff of Carnegie Mellon University have documented a disturbing fact: becoming more familiar with a subject does not significantly reduce people’s tendency to exaggerate how much they actually know about it. That’s why “investing in what you know” can be so dangerous; the more you know going in, the less likely you are to probe a stock for weaknesses. This pernicious form of overconfidence is called “home bias,” or the habit of sticking to what is already familiar:
In short, familiarity breeds complacency. On the TV news, isn’t it always the neighbor or the best friend or the parent of the criminal who says in a shocked voice, “He was such a nice guy”? That’s because whenever we are too close to someone or something, we take our beliefs for granted, instead of questioning them as we do when we confront something more remote. The more familiar a stock is, the more likely it is to turn a defensive investor into a lazy one who thinks there’s no need to do any homework. Don’t let that happen to you.
―The Intelligent Investor, Commentary of Chapter 5
持っている物を高く評価してしまう効果：endowment effectに加えて、よく知っている物事を高く評価してしまう効果：home biasが登場した。良く知っていることはむしろ盲目につながる。気を付けないといけない。ともに人間の虚栄をよく突いている概念だな。