When you get the realistic accurate numbers, you'll see that USAFA has an historic acceptance rate of around 15%-17%.
I've done a few college fairs as a volunteer alumnus for VMI. I tell kids considering our SMC (as well as other SMCs/ROTC) about the SA acceptance rates by stating that, historically, 85%-90% do not get accepted, and that there is nothing wrong with you if you fall into that overwhelming majority.
I always encourage them to apply to the SA first, but tell them that they will have plenty of company in the "Plan B." Psychologically, I think that lessens the blow of the reality of SA admissions for many kids.
For people who earn the appointment, they should be very proud to be part of such a small minority. Sometimes on this forum, I read posts from parents or applicants who have gotten the TWE, and they talk as if the world has just collapsed. It is tough to get told "no," but I wish there were more posts that emphasized that while it sucks, it was a long-shot to begin with, and that you can still pursue other ways to get to the end goal. To be fair, there are plenty of encouraging posts which tell the applicants to re-apply and to study hard in their Plan B. I also want to point out that a second application is something that should be considered in the context of where you'll be the following year. It's easy to say, "oh I'll go to Virginia Tech and apply to USAFA again" when a high school senior; however, you just may find that after a year at Tech (or at Texas A&M/VMI/University of Maryland/James Madison, etc.) that such an option becomes less and less appealing. On the other hand, the drive to attend an SA may never falter.
It's just important to know that priorities change, and that a TWE received from a SA doesn't mean you'll be a failure in life. Who am I to say? I'm a guy who got a TWE from a SA. I wanted to be in the military throughout my childhood, and I worked hard and applied to USMA as soon as I could. I was told "thanks, but no thanks" and went to VMI. I found myself drawn to the Air Force while a cadet, and the experience was great. I got commissioned, but after four years decided that maybe I was too hasty in thinking the military was a good option for a career. Don't get me wrong, I value my time in service; however, as can happen, my priorities and outlooks changed as I got older. What did I do? I got out and went to law school, and now I work as an attorney helping veterans. I would have never seen myself in this position as a senior in high school, but I'm pretty darn happy.
I think about this after I read every "what are my chances" thread. This isn't really directed at the OP, per se, as it is to all new candidates.
Good luck in the admissions process.