That's why you need to choose your battles wisely. Don't think that you can find an excuse to get into a street fight or a violent situation and expect your training to save you 100%. You are responsible for the actions you take or don't take. Sure you might get into a fight and win once or a couple of times on the street. Nonetheless, you will eventually come across a situation never encountered before and you could get hospitalized or killed. If you end up in a hospital, don't go around playing the blame game then claim that what i or others showed you is completely useless.
Want to know who your enemy is? Look in the mirror. That's your enemy. Fight your own ego because that's what could potentially cause your downfall if you get too ahead of yourself. The best combat training is one that you won't ever have to use in the streets.