I come from poor white trash, but I worked hard - got a Ph.D. from a top English university (I grew up in Canada), and now I work in DC as an overpaid consultant. I drive a fully paid for BMW, am looking out my window at an awesome view of the Capitol Building as I type this.
Hard work does indeed pay off, but you also need to make smart long term decisions with it.
Regarding the nurse and teacher - they do what they do because they like it. I understand, I volunteer 700+ hours as a firefighter in one of the rural communities here.
Work hard, but find a balance - that's the key to success / happiness.