For example, if someone is born into a struggling family of manual laborers (or a discriminated minority), but is smart and ambitious, how easy is it for them to get a good education and become someone important?

And speaking of social lifts, are there any that work better than trying to get a white-collar job if you're someone from a family of nobodies? For example, joining the army to become a general, or joining a trade union to become its head, or becoming a priest to become a bishop?