Contrary to the belief of many, it is impossible to predict who will become a Talmid Chacham. As the Chazon Ish said, “Every student is a possible godol hador”. The Roshei Yeshiva of today were not all the ones who people thought would become the Roshei Yeshiva of today. And vice versa. Talent and intellect help, to be sure, but effort and siyata dishmaya are more important to success as a Torah scholar. Becoming a “godol” is not just for the brightest. In fact, often it is not they who attain that goal. An average student, and it has happened that also below average students, have become great Gedolim and surpassed their more talented peers. Not everybody can become the greatest Talmid Chacham in the world. But everybody can become as close to the greatest Talmid Chacham in the world that he can. Those Bnei Torah, the ones who pour their heart and soul and life into learning Hashem’s Torah, merit, every single one of them, the greatest share in Olam Habah possible.
That is the main reason people learn in Kollel. Because Talmud Torah Kneged Kulam.