First of all, I think one of the important reasons is that the Qing royal family got married too early. Generally speaking, the normal age for men to get married at that time was sixteen, but for members of the royal family, it was even earlier. They got married early so that they could ascend to the throne as soon as possible. Because the rule at that time was that only the married crown prince could ascend to the throne. On the other hand, the emperor also likes to marry the prince, which also causes the prince to get married prematurely. This creates a problem. These princes began to be fathers before their bodies were fully developed, and their descendants did not develop well. Children born to women of this age are prone to congenital defects, leading to premature death.
In addition, it is inevitable to be born in the royal family, intrigue and intrigue. Princes involved in the power struggle will be targeted and calculated by various forces, including their brothers and sisters and even the closest people around them. This indirectly makes it difficult for them to become victims when their strength grows.
Generally speaking, being born in the royal family is their innate destiny. Either die young and become a victim of someone else's boss, or get through it and monopolize the power.