<p>Rayan, here’s your problem. In the context of university admissions, in America both “safety” and “back-up” plan mean “an option, usually a less desirable one, that I’ll use if my better options don’t work out.”</p>
<p>You seem to mean that you’re going to make an attempt at getting into MIT and some Ivies, and see what happens. The idiom you’re looking for, if I have understood you correctly, might be “reach” or “long shot.”</p>