Being a Black belt is not about how well you fight nor about bragging about it either. It is more the ability to teach and pass on to others the art. Bragging just brings on trouble and we train to fight so we do NOT have to fight.
So sure most probably are but that is just the beginning, graduating High School so to speak, their are levels above the Black Belt varying on styles. The young may love to fight or compete but as you age, you care more about avoiding injury to your family and self when ever possible. I would assume most Black belts surely know how to fight but it also depends on how they earned it also... was it earned through years of hard training, sweat and more or did you pay a lot of money with a guarantee in two years you will be one... so this is in a way a tricky question.
I do not believe personally in buying a belt, its a piece of cloth anyone can order online and fake a certificate, hence why I ALWAYS check references of students with past experience to assure they did not leave in disgrace or in a bad way. For many say for example that are Disabled yet are Black belts they may not be able to perform themselves certain things but they surely can teach others to do so.. for me I respect a good instructor over a good fighter any day.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.