Your post read my mind except #3, I got that nailed w/ a beauty. No complaints. As for #1/2, I think there is more to it than that. My myopic view of the posts/articles from various is as follows:

1. There are posters (regardless of platform) who want to garnish attention either to...

a) get a job, since visibility is how you attract attention good or bad.

b) Plato stating this the best for #2: “Wise men speak because they have something to say; fools because they have to say something.” ― Plato I personally fall under both categories depending on subject.

c) Bored, depressed, immature commenting as the latter part of quote in #2

d) Genuinely cares and has something to contribute, this now being the "wise men" of Plato's quote.

e) Want/looking to be tribal. Genuinely lonely, wanting, needing to be a part of a collective.

2. Speaking of both Ask / Show HN, I feel most do genuinely want to know and/or what to show like your own and unlike most other platforms. Here on HN, 98% of the time, you will get sincere responses. Thus my love of HN. Unlike the narcissism in 60% of Reddit, 99.9% of 4chan and 99.99% of FB...most being just a cesspool of wasted bits.

Now of course speaking only for myself. Here is me:
1. I'm an implant from Midwest to silicon Valley. Been here >20yrs.

2. what I miss dearly are conversations with well read individuals. I love the people I work with, with most having superior intellect to me however, English not being their primary, more sophisticated conversation I cannot have. I love my friends who came from afar and enjoy talking to them but I do not get the "tribal" connection I seek of being more alike. I get this "conversation" here in HN and nowhere else.

3. HN posters and commenter are like none other outside of StackOverflow ;). What I love about HN is the makeup of individuals who sincerely have something wise to say. I like to feel I'm well read and bread (not genetic ;-) but when i read people's comment like on this post, I literally take something away from every single commenter. It's overwhelm and I sometimes swell up because it gives me the connection I currently lack due to Covid lock down. The overwhelmingly well thought out and thought through comments feeds my thirst for knowledge and soul.
From what you seek, although i would still encourage for you to checkin HN for such support and topics, but goto somewhere more specialized to your needs like Indiehackers.com

Also look into this post and many others like it that seems to come up periodically as some having the courage to say they are lonely..https://news.ycombinator.com/item?id=26293703

PS> It's the worldwideweb with no barriers to entry including negative AI bots which I feel are being strategically inserted by foreign or internal agents. Sun Tzu said it best, "To secure ourselves against defeat lies in our own hands, but the opportunity of defeating the enemy is provided by the enemy himself." Somebody has literally taken this general's advice to task. It's unreal to think that someone can let a bot roam and disseminate seeds of self destruction to break a country down from within. www has become a very very scary place. Topic for a diff post ;-)

PPS> I'm guessing you're in your thirties, single, living in a metro, disheartened by the pandemic and frustrated in not being able to find a clear path to fame, fortune and independence. Although I am a bit older, join the club! :)

PPS> Just had an epiphany that we all need besides a soulmate, is an intellectual mates too? I feel that's what I'm searching for....