Human naturally have pride and ego and do not want to be told they are wrong and have made a mistake. Except for human beings who are objective, logical and open to new ideas, some feel embarrassed when you correct them and they feel like you are trying to pass a message across which says you are dumb, I am smart. Some feel that you correcting him is a negative attitude.
Lack of maturity is also one of the reasons people get angry when corrected. Some want to win am argument at all cost even when it is glaring that they are wrong. They believe you are the one missing the point they are trying to make.
It however also depends on the manner with you the person who is correcting is making the correction. If you rub off as very knowledgeable it might be offensive. Correcting someone in public can also be embarrassing leading to anger. Also when the person correcting is known to always want to correct people, this can also get the person being corrected pissed off or angry. The tone of voice used to correct someone can also be a reason why people get angry when corrected.