Students end up transferring for lots of different reasons (finances, change in major, fit). When I see a student contemplating a transfer before even enrolling, it raises a red flag. The risk of setting foot on campus on day one with a foot already out is you don’t make an effort to find your place. Your LORs from professors and college ECs are important when transferring and I think it’s hard to be authentic in your involvement when you are looking for the exit.
ETA What if you have an unsuccessful transfer application cycle and you are “stuck” at the first school? Better to try for a better option on the first go around, IMO.