Similarly, entertainment preferences are correlated with social class (and with income), but again, they are not perfect predictors of each other.

So a few anecdata wouldn't undermine anything here. Though in fact, your example actually strengthens the argument I am making: you are the kind of person that prefers watching documentaries over other drivel, and you are the kind of person who managed to get themselves out of poverty. That's likely because you have the preferences, habits and skills of someone who is at least middle class in a social sense, even if your income took a while to catch up.

(Keep in mind that we are talking about social class in a rather abstract fashion here. German middle class mores are different from American middle class mores.)