Is this the main reasons and logics why the cadet branches in the royal family exist?
In history, why did there exist the so-called cadet branch in English? First of all, as long as a monarch has more than one son, this situation will happen. Because the throne is exclusive, unlike property that can be divided equally, if the monarch has four sons, only one of them and his male descendants can inherit the throne (reasonably, the eldest son in principle), so The second, third, and fourth sons of the monarch and their male descendants are bound to be unable to inherit the throne, and they will therefore form the cadet branches (aristocratic family with royal blood). This is the reason and logic for the existence of the royal branch.