Learning from mistakes doesn't work the way most people think.
If you do something wrong, it's wrong. When you recognize and acknowledge that it was wrong, it becomes a mistake. Repeat a thousand times, and the only thing you "learned" is one thousand mistakes not to make.
But that doesn't mean you know how to do it right! Learning only happens when you take responsibility for the mistake, take steps to correct it, and do it the right way next time.
Let's use a sports analogy. In swimming, good form matters. If a swimmer's bad form goes uncorrected, it becomes automatic. No amount of determination or brute force will take her past a certain performance threshold. If a coach sees her bad form early enough, she can step in, provide direction, organize practice opportunities, and guide her to a breakthrough.
If you see someone who is in the wrong, step in. Offer to help. Point out what's holding him back. Walk him through the right way. Provide practice opportunities. Celebrate with him when he succeeds.
If you're wrong, acknowledge it. Own it. Correct it, and repeat it until you get it right. The alternative is to stumble through life saying, "Oops, my bad." Be careful though, you may not get 999 more chances.