Life is a combination of pain and pleasure. Young children cry when they can't have what they want. Parents so identify with the child and the tears that they can't bear not giving them their heart's desire. But it is not the best thing to try to keep your children happy all the time. That is not the way life is.
Many goals involve pain to get there.
That is the human condition. When children find this out too late in life, after being sheltered and buffered unrealistically, they will find things difficult and frightening to cope with. There is no way over-indulged children are going to be happy, because they seldom get direct honest responses from their parents. These parents are basically negligent. Children are begging for discipline and for structure.