The problem today is that parents cannot enforce boundaries. They are too lazy to do that for misbehaving children when they are young and when these children get older and they grow up selfish and spoiled the parents certainly cannot enforce boundaries at that point. Many parents today are simply scared of their kids. So the kids end up getting and doing what they want.
Chinuch starts from a young age, you cannot expect children to listen after they already developed themselves. Consistency is very important, you cannot let yourself be swayed by kids to change what you feel is right or wrong. Punishment for misbehaving should not be only an empty threat, it must be enforced.
At the same time, parents must respect children for who they are, with their own characteristics and individuality, and not force them into a mold.