Also, here is something that I don’t think you understand. Yeshivas that insist that its bochrim devote themselves 100% of their time to Torah, and do not allow college classes, don’t necessarily view those attending college as “failures who need to be kicked out”. Their point is that in order to maintain a high level of seriousness, its talmdimim must be focused, to the exclusion of other focuses.
There are plenty of very successful bochrim who have chosen at some point to leave full-time learning so they can earn a parnassah to support themselves and their families. That is very important, but that doesn’t mean it should happen while the bochur is in the yeshiva.
Many years ago Harvard (or another one of the ivy league colleges) had a rule that you were not allowed to be married while a graduate student there. The idea was that if the institution is supporting you, then you need to be 100% focused on what you are studying there. Of course everyone has things on which they spend some of their time, but the schools did not allow its students to have serious responsibilities outside of their “learning” lhavdil. The importance of focus is important, of course, in yeshiva just as well.