Yeshivos offer close to the same amount of credits peer semester that colleges do. If he has aBA whatever it becomes necessary to leave Yeshiva, he is only two and a half years away from a degree. This is not such an extreme amount of time. Meanwhile, there are plenty of jobs that a BA qualified you for that only require a minimum of training and pay respectably. From a financial stand point, kollel is viable, besides for the fact that hashem supports those that sit and learn his Torah. That is the lesson of the Tzinetes HaMann.
