Tele brings up the pertinent question, the morality of exposing oneself to serious bodily injury. The Church severely condemned duelling, for example, because it was an immoral custom. But fighting competitions do not attain to such extremes; there are rules that protect the fighters. Serious injury is rare and such an occasion can be made remote by level of expertise.
The motive for entering into such an endeavor also factors in to the morality of the activity. A man consumed with self-love, hatred and the socio-pathic need to inflict harm on others is evidently objectively evil, whereas a man who enters into this sport to help support his family has a laudable motive.
As to the practical comments on fighting, they usually end up on the ground and if you don't know what to do on the ground you will lose. Thus, the focus on ground technique. This is especially true when you end up on your back. Without training, one panics and loses the ability to engage in the fight.
I have previous 10 years of experience in Tae Kwon Do/wrestling and enjoy combat arts (I probably would have become a Catholic Knight when Christendom was alive and well). I have the spirit of a fighter for a just cause, either naturally or supernaturally. The reason I present this question is because we are in need supplemental income and I possess an skill that could possibly help. Whether or not I can attain to the status of being a paid fighter is questionable as I am currently out of shape and 35 years old.
The environment wherein these comptetitions takes place is certainly satanic, but I consider any arena sport environment satanic to some degree. Of course, I consider modern offices as satanic as well, or anywhere unbelievers set up their organizations, so any environment where I may work is less than desireable, but I refuse to concede that one necessarily consents to such evil simply because one works therein.