Irrespective of the book, might we have reach a point where our productivity is so high that we are not fully occupying the operational needs of a 9-5? Thus al

Irrespective of the book, might we have reach a point where our productivity is so high that we are not fully occupying the operational needs of a 9-5? Thus allowing time for a side-hustle ? I.e., We work salaried for 30+ ours per week and have time to spend on other activities for the remainder.