I'd argue the opposite of your headline, that this was a very successful launch. Since HN isn't your target audience having your site fail from the traffic was

I'd argue the opposite of your headline, that this was a very successful launch. Since HN isn't your target audience having your site fail from the traffic was far better than having it fail from a launch in your market. You shook out some important bugs before you lost real users. Plus you got to do this followup which will bring even more traffic.