If you're genuinely considering closing the doors because you didn't get into YC, that's really good evidence that YC made a good choice in rejecting you.

Take it as a slap in the face if you want. Be pissed. Cry like a baby. Throw something at a wall. Those are all perfectly valid, but the best YC applicants are the ones that don't need YC at all, so if you want to better your chances for the next round, prove to them how stupid they were in passing you up.

Or pivot!