ON THE OTHER HAND, life can throw you some very strange twists. My DW ran away with another man, my wonderful dog died, my only daughter graduated from university and moved across country and suddenly I felt very bored with my social life (ie, cocktail parties, barbecues) my old hobbies felt stale, and my doctor said if I twist another knee joint or sprain another ankle again - I can forget about the sports I like.
Truly enjoyed my work, but other things looked inviting too. Bottom line, I began traveling and discovered a whole new world that excited me from morning to night. I was able to transfer some of my skills as a civil engineer to teaching basic engineering calculations to workers in undeveloped nations. Basic earthquake-proof construction, etc.
Life can throw you some curve balls... so don't discount the benefits of being prepared for the unexpected. If you are financially independent at age 50 your options are wide open, including continuing to do exactly what you want or moving on. The joy is having the choice and not being trapped.