Housel explores how people have very different personal financial goals and perspectives, but sometimes mistakenly view investment through a lens of generic rationality. He explains that economic “bubbles” are not just the result of investors’ greed, but are created by people imitating other investors’ behavior, in spite of their different short- and long-term goals.

Housel condemns the notion that there are general investing rules that can apply equally to everyone, saying it “seems innocent but has done incalculable damage” (151). Different investors have “different goals and time horizons” that make it impossible for everyone to follow the same investing strategy (151). While to outsiders it may seem illogical for investors to buy very expensive stocks, it can make sense for day traders to do so, since they plan on selling them in a very short time span. “Flippers” use the same approach: they may buy homes or other assets as prices soar, and then “flip” them months later for a profit (153).

These approaches may be risky or even irresponsible but not irrational, since many investors do profit from pursuing such short-term investments. According to Housel, bubbles can become damaging when people with long-term goals begin to imitate how day traders tend to operate.