Well, the honest answer is that it does apply to everybody whose main income is not investment or anybody who must remain employed in order to survive. We live in relative luxury and privilege, but many of us certainly might not work for their current company or as many hours as they do if they had the freedom not to.

As LesZedCB points out, it does apply to everyone whose main income is the sale of their labor. Software engineers could be considered part of the [aristocracy of labor][0], but still part of the working class.

[0]: https://en.wikipedia.org/wiki/Labor_aristocracy