Different prof here, but a few thoughts:

• academia is not as shiny as it sometimes seems, but it can be great. You can have a lot of freedom to do what you like, work when you like, how you like… do meaningful things. Not always, but the chance is there
• it’s not to get rich. Selling expensive textbooks is rookie level exploitation compared to what people do in the industry, and most of the profit doesn’t even go to the prof

The book to read for this is “the professor is in”. The author takes quite a cynical perspective about academia, but in many ways it’s true. Worth a read (and probably you can get it for cheap second hand)