As many current and former university students (myself included) will tell you, you don’t have to be smart to succeed in university, you just have to be smarter that the other students in your class. This is called surfing the curve, because regardless of how bad you may be in an absolute sense, as long as you’re good in a relative sense, you should be OK; if you’re above average, you’re pretty much guaranteed to pass and continue on to the next course. Curve surfers benefit from other students’ lack of attention, attendance, and interest in class; it’s not that they’re particularly bright, it’s just that they’re less dumb than the others. A cynical philosophy, it’s true, but not at all uncommon.
I was reminded this weekend that the same principle applies to politeness, and the result can put money in your pocket.