Since you've mentioned you're also interested in non-romantic relationships, I (late 20s M) have been casual dating on Tinder for four years. I tend to select my matches based on how attractive they look to me. Most of my dates are students in humanities or arts, service workers, or working professionals in non-STEM fields such as hospitality or translation. Programmers, models and blue collar workers are rarer.
On the first date I typically start with FORD smalltalk topics (family, occupation, recreation, dreams). I discovered that this approach doesn't always need to be boring - I can ask my date about what would she do with a billion dollars, or tell her about the time my organoid kidneys got transformed into beating hearts during my PhD research. This prompt often leads my date to ask: "you're not going to steal my kidneys, are you?", to which I reply: "I'm the least likely person to do this - if I need some, I will just grow them in my lab".
After that we can transition into our topics of interest (that is, if we're not making out yet by this point). Last month I invited my match on a first date to a bar where I told her about Fermi Paradox, then about AI alignment, then I asked her whether she would take hypothetical anti-aging pills, then we kissed and went to a love hotel. Two months ago, on another first date my match spent 90 minutes trying to solve a simple logical riddle, then gave up and left. I didn't hear from her again.
Irrationality is one thing I found hard to deal with - for example when my date brings up astrology signs. At first I was very argumentative or tried to convince my date that she's wrong, but that tends to go poorly. Nowadays I simply switch the topic to my love of astronomy, or play a little prank on my date:
"What's your sign?"
"I don't remember"
"Well, what's your birth date?"
"It's in February"
she pulls out astrological sign table
"Well you're Pisces then"
"I'm pretty sure February 30th is not on your calendar"
The majority of my dates I only see once or twice, but some of them transformed into friendships or FWB-type relationships. Many of them live in other cities or abroad, but they call me up from time to time when they return to my city. We also keep contact through social media (Instagram).
I'm happy with my dating life and with people I meet - I just wish it was more frequent and less expensive. Almost all of my dates are nice and kind people, some of them can have interesting conversations or can point out my flaws and improve me. My dates also tend to drag me out of my comfort zone and give me a reason to try stuff I would never try for myself, like spontaneously flying to Amsterdam or going to a trampoline park. As for the deep discussion of rationalist-adjacent topics, I'm quite satisfied just talking about them online or with my IRL friends and coworkers.
What does "±8 relationships" mean? Is that a shorthand for 0±8, and if so, does that mean you're giving the range 0-8, or are you also claiming you've potentially had a negative number of relationships (and if so what does that mean)? Or does it mean "8±n relationships", for some value of n?