How do we balance between an individual who is qualified to seek Islamic knowledge and is able to dedicate time to it but does not do so, and the fact that seeking knowledge is a communal obligation (fard kifaya)? And is he sinful for not utilizing his time for that purpose?

Religious knowledge is divided into: an individual obligation (fard ayn), such as the fundamentals of religion and basic acts of worship; a communal obligation (fard kifayah), such as jurisprudence (fiqh) and Qur'anic exegesis (tafsir); and a supererogatory act (nafl). As for beneficial worldly sciences, they are either a communal obligation or permissible. Seeking religious knowledge is considered one of the best deeds after the obligatory duties, and it is superior to voluntary jihad and other acts of worship, due to its benefit to the Ummah and because scholars are the inheritors of the prophets.

If a person is free and has the aptitude to seek knowledge, they miss out on much good if they limit themselves to learning only what is obligatory. It is also advisable for a student of jurisprudence to begin by studying a specific school of thought (madhhab) and mastering it, then expanding to study the rest of the madhhabs.