I always like to think of self control the same way as free will. A useful abstraction, but not something that really exists. It is obviously beneficial for a person to believe that he is in control of his choices, of his behavior, because that increases the chance that he will take action to improve his lot. But that it is useful does not mean that it exists.

Has a child of christian parents who have never heard anything but religious music, books, stories, people had the opportunity to make a free choice? I don't think so. Has an American child who has seen thousands and thousands of ads for garbage food taken an independent choice to eat that? I don't think so.

We humans have precious limited mental resources and can’t afford to spend the time considering every decision rationally; therefore, we automatically subconsciously make decisions based on salient features of the current stimulus. In normal words, we make shortcuts based on limited information.

Since people are so very irrational (See Thinking fast and slow by Daniel Kahneman) the idea that we are rational can be used as an excuse by those (advertisers, politicians) who want to manipulate us. So, it is in fact a dangerous idea.

I sometimes entertain the notion that it would be better to live in a totalitarian dictatorship where some benevolent dictator manages the information people are exposed to and thus makes people make better choices of their own free will. (I'm aware that such a society has some dystopian aspects as well, of course)