In fact, every parent will calculate the fortune for his child and see what his fate is, but it doesn't mean that he will calculate it for what he gets. ...

Is it necessary to calculate a child's life in order to get something?

No. Because children are still young, many things are worried by adults. Fortune-telling is to choose good luck to avoid evil spirits and help adults take better care of their children. Your idea like that distorts the nature of fortune telling.