The well-off have been enriching themselves by exploiting the labour of the working classes for centuries. The form changes with historical shifts, but the function stays the same. Most of the time it's not intentional. You're born into your position and benefit from it without even recognizing the exploitation taking place. Even those being exploited don't tend to recognize it because the exploited aren't the ones controlling the national narratives about their exploitation. They tend to buy into the ideology that they need to pull themselves up by their bootstraps. However, if hard work was all you needed to be rich (as opposed to opportunity....which often comes as a result of heritage), I know people working in auto factories in Windsor and Detroit who should be worth many times more than Donald Trump.