I think some people sabotage relationships for the same reason they throw video games. They have fears/suspicions that it’s going to not work out, and rather than be a victim they want to have some control over the outcome. A loss or failed relationship doesn’t hurt as bad if they caused it to end the way it did.
However in your case, it sounds more like a fear of something different. It’s a lot easier to keep things like they are, when a relationship gets too serious or life impacting it can be easy to be scared of the change, and instead subconsciously decide you want to keep things like they are.
It’s not like the current group of users is perfect either. There’s a lot of circlejerk opinions going around, and I’ve seen being get majorly downvoted for posting factual info that went against the “hivemind” opinion.