Is the acquisition of Islamic legal books—given the ability to purchase and read them—considered extravagance, especially the book "Siyar A'lam al-Nubala'" which scholars have recommended?

The presence of beneficial religious books in the home is very important, and the book "Siyar A'lam al-Nubala'" (Biographies of Noble Figures) is one of the most important books for refining conduct and upbringing. Its language is easy and it is engaging. It is recommended to buy this book for children, and the existence of unread books does not prevent the purchase of new ones. Inheriting beneficial books of knowledge is an ongoing charity (sadaqah jariyah) and knowledge from which benefit is derived, as the Messenger of Allah, peace and blessings be upon him, said: "When a person dies, all his deeds come to an end except for three: an ongoing charity, or knowledge from which benefit is derived, or a righteous child who prays for him." The inheritance of beneficial books can be likened to the inheritance of the Mus'haf (Qur'an) mentioned in the weak hadith: "Indeed, among what continues to reach a believer of his deeds and good deeds after his death are: knowledge he spread... and a Mus'haf he bequeathed." Obedience to scholars is obligatory if they guide to what Allah Almighty has made obligatory, not in matters that are merely desirable, such as buying books.