Definitely! They forgot that there are two type of revenues for a company, and that it can be applied for personal finance as well :

Operational revenues : the real job, the thing that is making money. The yield on the operational one is

Financial revenues : cash sitting around non-invested yet into operations, waiting for the next project to invest in.

The yield on the operational revenues is much higher and the investment in it could be transposed as for example : spending for some certifications, go to online or physical classes, etc