Google is your friend.
With 6 year grad rates ranging from about 95-97%, there just aren’t that many spots to transfer into. Some reports show, eg, Harvard taking roughly a dozen kids out of more than 1400 applicants. I’m not going to google the most recent exact numbers, but you may want to.
Plus, getting a transfer admit demands a rather specific need. Notjust that a kid wants to retry to get in.