"If you spend your entire life never needed to use the skills of karate for which you trained diligently for such a long time...you truly have accomplished the goal of your training. Learn the art of killing, without ever taking a life." Chotoku Kyan. 1942
In addition to what Master Kyan said, I have some more specific reasons for my "No!"
Even if you never need to use your skills for self defense purposes you still...
- Have a healthy body. You have defended yourself against obesity, poor health, etc.
- Have learned about discipline and helping others.
- Have gotten valuable life skills such as public speaking.
- Have had fun!