It's time for "answer a question with a question"!  The answer to "Do Martial Arts REALLY work" is "Does football REALLY work?".
To paraphrase Bruce Lee, if you learn how to "do" football and you lose a game, it doesn't mean the plays were bad.  It doesn't mean the technique of throwing a pass is no good.  It means simply that you have not developed the attributes required to apply those skills against that particular opponent.

     Martial arts seem to provide a never ending showcase for self-delusion.  It was only natural that fraudulent schools of "Kung Fu" would spring up across America when Bruce Lee made Chinese boxing famous in movies.  Likewise, in the 80s it was hard to walk down the street in any town without running into would - be "ninja".
     Frauds and cons have been with us always.  That is no surprise.  What IS  amazing to me is the number of people who manage to con themselves. 

Look at the video here.  Consider that somehow, this "master"'s students have become convinced that he has a mystical power to paralyze them with his Ki - the mystical "life force".
 

Paul Vunak once shared this illustration with me to demonstrate the fallacy of "style vs. style" thinking.  Imagine 3 experienced fighters.  

Fighter A is a professional heavyweight boxer.
Fighter B is a jujitsu wrestler.
Fighter C is a karate man.

In fight 1, It's karate vs. boxing.  The boxer is agile and fit, but when he closes the distance, the karate man snaps a kick to his groin.  The boxer, unfamiliar with the low kick and unable to block it, drops his hands in agony.  The karate man is able to kick him in the head and run away.  Winner= Karateka.