Ok there are a lot of points that are being over looked or missed. Most of what Vista123 said is correct and from what I have seen based on going through NASS and then being on the other side of things and being a detailer for NASS last year, there's a lot of things to consider, and sorry in advance for the long post.
I agree that the "Only 1/3 of the current midshipmen class did not attended NASS" is very misleading. A sizable portion of the Brigade are prior enlisted who came directly from the Corps or Fleet (some going through NAPS). Also considering ~17k applications to the academy vs. the ~5k applications to NASS is also a huge indication that many didn't know about or consider NASS before applying to the academy. Many others who went to NASS were also considering other academies and went to WP's SEL program or USAFA's summer program as well and ended up pursuing those schools instead (But I can't see why
).
As for "Everyone who I know who did attend NASS didn't get in" is a huge generalization. Some Personal Stats:
--Of the 10 people in my squad when I did NASS, 8 of us finished the application for USNA, 3 of us got an appointment, 1 got into USMA.
--Of the 21 people who were in my squads last summer when I was a detailer, 17 finished the application, 7 got an appointment, 1 got accepted into NAPS, 1 got an appointment to USMA, USAFA, and USNA. (and there were a couple people who I did not think met the qualification of the academy at all that still got into NASS, but not the academy)
Even more so, the majority of people in my company now didn't go to NASS because they didn't hear about it. And after doing a quick company poll, 11 people out of 39 in my class applied for NASS, got rejected, and are still here (and a lot of them had better resumes than me). Only 9 of us went to NASS.
This brings me to my final point, and why I don't completely agree with Vista123; The Application for Summer Seminar is not as comprehensive as the actual application and doesn't always give the academy the full picture of who you are. Also if your brother or sister is a USNA grad, you might not be accepted since you should have a good idea what the academy is like through them, and there is some truth behind geographical location and acceptance. If you live within a 100 mile radius of the academy you'll have a harder time getting accepted to NASS since you're expected to have more opportunities to visit the academy (this does not apply to CVWs). So don't think you don't have a chance of getting into the academy if you're reject from NASS cause that's not true. That being said, no matter how good you think your package is, you should be striving to make it better.