What do you think of my sister's statement that there is no need to marry due to the absence of problems, the lack of guarantee from a husband, and the difficulty of raising children?

Marriage can be subject to the five Shari'ah rulings (Wajib, Mandub, Mubah, Makruh, Haram). Deliberately abandoning it without a valid reason contradicts the command and Sunnah of the Messenger of Allah, peace and blessings be upon him. It also entails missing out on great benefits and noble objectives. Marriage is not solely for fulfilling material needs; rather, it was legislated for other purposes such as procreation and chastity. Therefore, the thought of abandoning this great Sunnah is incorrect.