I read blogs in which the FIRE writers mentioned on the need to have the side hustle in which one can retire to, after calling it a day on the full-time employment. Based on my perspective, this appears to be a valid point. On the other hand, I feel that it may be best to leave the side hustle to the natural. I believe that the things will form up and occur naturally when one quits the full-time employment. I guess that it is likely due to the fear of nothing to do after quitting the full-time employment.
I also read the phrases in which states that one will regret things he/she does not do after 20 years. This is a valid point. If one does not do anything, one will never know what the outcome of the wishlist (since the action is not taken).