<p>Backing out for reasons other than finances (or no reason at all) will absolutely affect both you and your school. You can lose acceptances to other schools because different schools work together to ensure people are following the ED rules. More importantly, I college will blacklist your high school because it is your guidance counselor who allowed you to apply to more than one ED (by sending transcripts to both schools) or allowed you to apply to schools after you were accepted ED, and because it’s really the only way for colleges to transitively punish students and scare them into not backing out.</p>