Over time, did it become easier or harder for people to go from “rags to riches”?

A recurring belief in American History is the notion of achieving status through merit: that people can significantly better their economic and social situation through hard work, diligence, deferred gratification, and a measure of luck. In the case of colonial Chesapeake society: Over time, did it become easier or harder for people to go from “rags to riches”?