A realistic perspective for non-elites to balance out opinions such as "applying will help you think through your idea" or "the upside is completely worth it".

1. Imbalanced niceness: If you get convinced or are in a good mood, you must know that YC is a private company that works to serve its founders, employees and current startups (any private individual would do that so nothing wrong!). The goodwill that is put into filling out a well researched application will be met in around 95% [1] of cases with a cold email with no feedback. The gain from "thinking through your idea" or having romantic thoughts of getting in will most likely be wiped out with the rejection trauma. Also, to temper expectations, it is useful to know that YC actively seeks elite networks with more vigor than the general public due to obviously higher odds of selection and future success of elite founders (again nothing wrong here but these things should be known by non-elites). Just search "yc mit" for how actively MIT alumni and students are reached out to by YC partners through in-person events.

2. Competition from elites: If a person with an elite background (company or university) applies with a similar idea to a person with a non-elite background, the elite person gets in due to stronger odds of succeeding in hiring, raising follow on money etc. The non-elite person's capabilities will most likely not be compared objectively to those of the founder with the elite background due to lack of resources. It will most likely be assumed that the elite person will pull it through rather than the non-elite. This is one of the reasons many highly capable non-elite founders feel a lot of whiplash because an elite founder with only an idea will often make it through while the non-elite won't. The whiplash originates from there being such small delta between the non-elite and the elite individual in many cases. The claim here is not that all elite get through. The elite are weighed with other elite but it's obvious that there are higher odds of getting through if you're an elite. It must be realized that just a couple hundred elite applicants will almost completely wipe out the odds of thousands of non-elites.

I'm a non-elite and I've applied and been rejected thrice and just don't have the strength to go for these schemes anymore. I know "we should learn to deal with whiplash" but I'm done with the way the world is designed. I believe the individual must rise higher than having to depend or listen to such schemes and feel pulled into them while in most cases ending up worse off in the process. Schemes such as these are designed to cause more whiplash to the non-elite without any fault of YC - this is just how the world works.

Follow up thoughts
Q- Why didn't the non-elite strive harder to become the elite when they had the chance?
A- I think we generally thought that we'll hit our home run at the next attempt but didn't know how quickly the odds slide to impossible. Also just ignoring the fact that the elite group is a relatively small and stable number of people that doesn't elastically increase with the population or with with one's capabilities. The elite just get more elite - the lindy effect.

[1] assuming 2% selection odds and 4-5% odds of an interview call