There could be a lot of different reasons why your "Show HN" wasn't successful. Applying that to every "Show HN" is not correct.

My experience was very different from yours. Stayed on the front page 16 hours, spot #5 for 5 hours (iirc). Similar to you, I had to work myself up to even submit it. I procrastinated 2 hours before posting. Only told 1 friend I had posted. However, I'd consider mine very successful. I did not expect it to be, because if I had, I would have increased the Digital Ocean droplet and my server would not have crashed. Of the ~5 hours I was at spot #5, my server was down almost 3 hours between 3 different crashes.

I say this on reddit often, between Show HN and PH, people give PH way too much credit. Show HN is a great launching platform, just remember who the audience is.