5% +/- 5% Much like the chances of every other sane candidate. Sure, some people will apply with poor stats just to say that they applied at Harvard (or wherever) the 2nd reply pretty well covered it. It is not about your resume, it is about what the school want in their class makeup and whether you happen to fit best…oh, and your interview/essays.
Even if those schools only took valedictorians, they would reject over half of the applicants. There are just too few spots for anyone to tell you that you have a good chance. Pick a solid safety and do your best.