First off, life isn’t fair. Second, unless you were in the room where the admission decision was made, you don't know that the other student was less qualified than you. Sure, he might have similar, or even lower, grades and test scores, but numbers aren't all there is in holistic admissions.
Simply put, college admission has never been fair to the applicants. Admission to a particular college is not something you earn or deserve. If your abilities match their institutional priorities, then you will be admitted. One of those priorities might be “We need more students whose wealthy families will give us money.” C’est la vie. Those students’ families are paying for other students’ scholarships.
But, if I’m correct in assuming that your “dream college” is one of those top 20 name-brand colleges, you need to face the facts that admission to those schools is not a given for anybody. There are more high school valedictorians every year than there are seats in the freshman classes of all the Ivies combined. I had a student last year who applied to all of the Ivies (against my advice). She had perfect grades and test scores, leadership, honors and awards, great essays, the whole nine yards. She was eminently qualified. She was also only admitted to two of the eight; two of the others flat-out denied her, the other four put her on the waitlist. Fair? No. Reality, yes.
So rather than grousing about the students who did get in being “less qualified” than you (which you don’t actually know), I suggest you rethink what you mean by “dream school.” Maybe that college didn’t see the fit with you. That’s fine. You have many, many other schools that might fit you better. Do some research and find that perfect school that really is your perfect fit.
P.S. I have yet to have a client still hate their college after completing first semester. Most realize by May 1 which school is their best choice. Others spend all summer languishing on the waitlist and trudge off to college reluctantly, moping about what might have been. All those students did was ruin their last summer before high school. By October, every. single. one. found that they really loved their “next best” school, and couldn’t imagine going anywhere else. Don’t start your adult life consumed with jealousy. That’s a terrible way to live.