For example, if the undergraduate graduates are 2 to 22 years old and the master graduates are before the age of 24, then the cost of studying PhD is not particularly large, but it will not be a good choice, because sooner or later you will have to face the problems of employment, choice and future again. And if in this case, you are over 25 years old, then it is really not recommended to study for a doctorate, especially for girls, because it is very important for girls to make a reasonable life choice at the age of 25.