If a man empties his purse into his head, no one can take it from him.

What you spend on learning ends up somewhere no one can reach. Property can be lost, a job can end, savings can be taken by circumstance, but a skill or an understanding stays where it was put. That is not an argument against saving, only a reminder that money converted into capability is the least losable form it takes. It also compounds, because knowing one thing makes the next thing quicker to learn.

If you are hesitating over the cost of a course, a book or a trip that would teach you something, weigh it against what else that money would become. Most purchases depreciate. This one does not.