You have to remember, HN is fully supported by YCombinator, and has a huge leg up on any possible similar sites. There will always be content thats encouraged to be posted here first from YC startups, and it will always be a valuable PR asset for those companies.
It doesn't have any pressures to make money, in fact it's basically a free place for PR and advertising jobs for portfolio companies
Generally, no, at least that I know of. Of the ones closely following the format, lobste.rs had a pretty good run, and designer news was busy enough to be worth visiting for a few years. With some more flexibility on format, product hunt might top the list.
HN is somewhat unique in its lastingness, and seems to have found a sweet spot in growth rate over the years that allows them to stave off the 3 things that will kill a website like this: silence, negativity, and grift. Most websites are so scared of the first one that they'll compromise on the second and third. Moderation is hard. Surely a large of dose of luck is also involved.
There's also the challenge of getting the right audience for the site, especially in the early days. Hacker News isn't just popular because it's a tech forum, but because it's one where many of the smartest, most resourceful and sometimes most powerful people in the industry are active members, and where the founder/lead engineer of a large company or project is likely to appear in the comments section.
A lot of other Hacker News equivalents don't have that, and hence end up being just another internet forum in a list of millions.
There's also probably the fact that the format works better for engineers than it does designers or artists or athletes or musicians, since the former tend to be more of a fan of 'simple' websites with utilitarian designs. A lot of clones try to copy the Hacker News style, only to realise that their target audience finds the layout ugly and offputting.
Facebook is a really good example of how sites can just grow on grift and negativity, then clamp down on it later. There was a time when the FB feed was overwhelmingly "help me water my crops in Farmville". Zynga became a unicorn and was eventually pushed off FB, but they're still making good money today, happy endings for all.
Fake news and unpopular opinions were also really big at one time. FB killed them, mostly by adjusting visibility of some posts more than others or burying the unreliable sites. It's also why people post links in comments though.
HN is a little different though - everyone shares the same "feed". Most social media show you what it thinks you want to hear. Whatever goes viral on HN is the same for everyone else. So you're also likely to be sitting next to someone with a political opinion you abhor. There's silent downvotes on certain trigger words, but in a sense that works too, because people just avoid topics that the community doesn't like.
I feel like Ask HN is also a vent for negativity, while Show HN is a vent for optimism and self-promotion.
It doesn't have any pressures to make money, in fact it's basically a free place for PR and advertising jobs for portfolio companies