If you're not surrounded by people who have had success in their careers / education, it's hard to know which opportunities are available to you. Often, you only know about your parents and their career choices.
Also, the problem isn't entirely that some people don't understand the value of "showing up". It's that they don't always where and when to "show up" in the first place. For instance, I know a first-generation college student whose parents, while he was in high school, didn't even realize college was an option for him until his teachers started pestering everyone about college apps. He was lucky to attend a school where most students go to college, but I can imagine that in a poorer area he would've missed the opportunity entirely, thinking that he's not smart enough (which he certainly was!).