I don't think that what you did could be make you a failure. That guy is a cocky jerk. What is did disrespected you, your instructor and the other people sparring that night. If your instructor did the same thing then I doubt that it really was wrong to do what you did.
I feel that it is easier to work hard when done in an fun way. I would work hard if all we did was exercises however it makes it alot more interesting. My Sensei always changes the main purpose of the class. One day it can be about DMMs and Kempos, next it can be about Katas. That keeps it from being too predictable
I hear a joke on Cartoon Network about Martial Arts all the time. the sad thing is, thanks to horrible movies and TV shows, people think that because you do karate you should be able to chop a brick in half. I usually don't tell anybody anymore so t really does not involve me but I'm sick and tired of the disrespect and expectations the Martial Arts get and recieve these days.