Whether you’re a Karate practitioner, MMA fighter, combat fighter or any other competition martial artist, you train for are a very specific arena, dealing with very specific parameters. Outside in the real-world, if you use those parameters, oftentimes you will find unskilled people, who just have the ability to want to hurt you, are going to be able to do so, because you are not able to play the same game as they do.
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These combat athletes are incredibly capable in their environment. But being confident (or over-confident), in a skill set that doesn’t apply in the real-world, is at the very least foolhardy, it is knowledge and skill that they just don’t have.
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As an example; you may have to deal with more than one person, or a group of highly agitated motivated, aggressive individuals, possibly drug fueled. A weapon comes into play, several weapons, you’re attacked from behind. Unlike your competition or tournament, it is very rare to find yourself in a one-on-one encounter in a street fight. How do you deal with these threats? These are things that are not normally covered in your typical combat athletes regime and most of them will admit that (if they have any common sense).
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Having success in an arena or being able to break boards, ice, bricks etc., or to fight (or multiple single fights) in a controlled environment, which ALL competition is; truthfully, it is NOT the real-world.
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Every martial artist, or martial art, that is of a competitive nature, has rules, referees and judges able to stop a fight. To prevent you from becoming seriously hurt. There is no such luxury in a real-world self-protection incident.
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Being very cocky, or over-confident, because of success in the tournament arena, taking that outside with a skill set that doesn’t apply in the real-world, is highly dangerous and downright stupid. Don’t have a false sense of security because of your abilities within the tournament and competition arena, thinking it will translate to real-world events. There are highly motivated, unskilled guys with determination to harm, not compete, that are out to severely injure you, or worse, with whatever means they can. NO RULES.
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To reiterate; there is NOT one system or style that is the best or strongest in ALL things. The realities of self-defense situations and street fights are harsh and the consequences are severe….. Don’t be deluded….. The goal is to live a life that avoids violence, not encourage it. 
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