The main thrust of your post is correct, but your characterization of the classes is... misinformed.
The poor and the upper class do what they want when they want? The middle class works harder than the working class? ...What?
In reality, the working class were terribly abused in the "old days." Their days were long and hard, and wage theft was (and still is) rife. For them, there was no such thing as a vacation, which is something the middle class could enjoy. The poor were much too sick and weak to do as they pleased. They had to continuously toil in things from begging and scavenging to odd jobs in dangerous places.
It is better to think of it like this. Your class depended on ownership.
Poor own nothing and in general doesn't have any way to benefit from their own labor.
Working class did not own their jobs, but did receive income from their own labor, though only a fraction of its value.
Middle class own their own jobs, keeping most of the value of their own labor.
Upper class own the means of production, keeping all of the value of their own labor, as well as the value of most of their employee labor.