RKD doesn't always have a ROI, but it doesn't need to - people attending those are usually very rich. They just want to stay four years away from their families, attending a multitude of classes, play instruments, join clubs and create their network of similar minded rich kids. They can stay even longer than the required time, for extra activities or pursuing a masters. Then they'll move on and get good jobs due to the social value of their diploma and network, and start to learn their jobs by actually doing them. Maybe those jobs aren't that good and don't pay so much, but it's in their passion and they have old money to spend on their passions.
TPF is for the not so privileged people, for the ones who have no energy to waste, need to learn useful stuff in the least amount of time. ROI is essential to those and if they could pay less, learn stuff on Coursera and get good jobs, they would.
So when accounting for the ROI of a college tuition, one must first separate the institutions into those two buckets, for clearer results.