Used to use YouTube, Facebook and discord. Just Facebook now. Not worth using the rest. The time vs income factor isn't worth it.

Use a few niche forums which brings the highest traffic. 

I just use Mastodon (see the link on my profile). That, and my own websites. Still the best way to have an online presence.

A custom website addresses most of your complaints:

• You may post at your own pace. People subscribed to your website may get notifications via e-mail, RSS, or whatever modern way the kids use now.
• The website is about you, so nobody may drown you out.
• Your site, your algorithm, if any at all.
• This is really a you problem, not the platform’s. You’ll always find something to trip and get depressed over, e.g. low hits in your analytics.

It needs more effort in marketing, but it’s not like platforms like Itch and Facebook do that for free, either.

To answer your questions,

1. Most of the time, tech and programming-related things, but really whatever I feel like.
2. Hobbyist.
3. I do run a tangentially-related Discord guild, so the overlapping demographic helps, but the guild itself isn’t centered on me so I try not to spam it.
4. The only external website I ever advertise at is Reddit, but results are always mixed, and I don’t really try that hard, anyway.

My analytics on Itch are satisfactory for me, with a mean of a hundred 7D impressions, with CTR bouncing between 0 and 4%.

One possibility I've thought of might be YouTube. And it's usually not a lot of effort. You just post a video every now and then and hope people see your page.

To answer your questions though:

1. Video games and other things

2. Hobbyist

3. One thing I do is post my game on Game Engine specific pages (ie, if I use GDevelop for a game, I might post about that game on a GDevelop page. If I use Ren'Py for a game, I might post about that game on a Ren'Py page. Just be honest about what engine you use, ie it might get bad reception if you post a Ren'Py made game on for example, a Game Maker or GDevelop page.)

4. Yes. Somewhat. Sometimes, the big platforms are looking for the "next big hit", so smaller games and projects might sometimes get overlooked. I feel I've actually had better success on smaller platforms.

    do I have to make do with these platforms I don't like

Well, for me personally, the beauty of being a hobbyist is that we don't really have to make do with any platform we don't particularly like - we can just leave off it and concentrate on developing things we enjoy, without the need for any external promotion at all. Unlike the folk who've spent money developing stuff and must make it back, I don't think I've ever suffered a loss not being on Instagram, Tiktok or Facebook. 🤔

Though, if it helps, you can try Reddit if you like. Granted, it is a big platform, but it's also discussion-based and the scope of our posts are usually only limited to a certain sub unless someone decides to cross-post it, so you can just hang around the small communities and post there. There are numbers involved, as per most platforms - karma - though that's negligible at best and doesn't hinder discussion or feedback in general. I've gotten some good feedback for two of my fangames there. The only original story of mine that got a number of visits from there was "The Swordsman Who Lost His Nipples", though, so I can't vouch for it 100% when it comes to serious stuff.

Alternatively, I'm also on Tumblr, which is smaller and more intimate than, say, Twitter. An interesting part of Tumblr culture is that folk who reblog our posts also tend to add "micro-comments" in their tagging system, making their reblogs a lot more personal. The site is slow and laggy at times, but the upside is that you can post pictures and format text there. It's customizable too, to a degree. In terms of promotion... just like Reddit, I've only seen my fangames do well there. My original stuff kinda gets ignored. (EDIT: I do see writers use Tumblr to get their works out, though. Maybe give it a go to find other writers there?)

That said, I do tend to prefer engaging in fast-moving platforms like Twitter. Twitter as a platform is exciting when it comes to speed, and I get to respond very quickly to other people's posts too. The best bit is that most posts are short and concise, and that facilitates rapid-fire replies, which adds to more replies from folk who see them in their own timelines. For folk like myself who're restless and like chatting others up, it's a pretty nifty platform to be on. My experience on Twitter has been good, even if I've slowed down lately due to login issues. I don't get too many clicks for original stuff there, but my fangame posts did balloon up like crazy.

As far as I know, though, self-published original games, art and stories can be pretty hard to promote on social media, even on the slower ones. Your best bet may be to join a Discord server and reach out to fellow developers. Some developers have a following that's comprised mostly of other developers. If it's "genuine" non-dev players we want, it's market research that we'd need to do before even making our game, let alone promoting it. That part's just as tricky as finding the right social media platform for it.

Good luck!