At the end of the day YC is just a business with the same goal as every other, to make money. They pick people and ideas aligned with their own interests. It a

At the end of the day YC is just a business with the same goal as every other, to make money. They pick people and ideas aligned with their own interests. It also seems to be that a large part of it is to find companies that are easy to pitch at demo day for future investment. It isn't a charity and given the number of applicants the chances are high that some other team has a more sellable or easier to market plan. For most of us that didn't get in the worst possible outcome is a bruised ego. Keep on working and see it as a chance to have a friendly competition with the companies that did get in this batch :)