A more general case of the red herring of meaning is that people go for what is “best” within their constraints, especially the constraints of what they believe Life can hold. For example:
“Do what you love” is constrained by the fact that modern work has no impact or freedom. I think most tasks can be quite fulfilling if you feel a direct impact on your environment or the people around you, and if you have a decent amount of freedom in how you pursue it, but this isn't how work is for most, which is why it is such a consistently miserable aspect of one’s life
Women go for assholes, because good guys, who have a heart but also a spine, are rare. Most guys are just cowards, in that they don't have a spine, and honestly they don't really have a heart either, they're just manipulative but in a less overt way. Assholes at least have a spine so it makes sense that women go for them, they are the “best” in a heavily limited pool of men
People aim for individual happiness, because belonging to something Bigger has been utterly destroyed by the modern world
“Don't pay attention to what people think of you” operates within the framework that your environment is fixed and you just have to deal with it. In reality, you can change jobs and get rid of toxic people in your life. It's not always easy, and when you're young it's not really possible, but it is worth considering. If humans are geared towards fitting in, then you can find a better social environment, one where “fitting in” is more aligned with what you really care about