People might have gravitated towards iPhones for status signaling in their youth, and by association and inertia, their inner circle uses iPhones. now, as adults, any person coming into the circle needs to conform to the group or be seen as clueless.
An iMessage chat tells me nothing about the socioeconomic characteristics of the owner of the iOS device, unless I am missing something.
Edit: although, now that I have read this whole thread, I am thinking that maybe it’s not the economic status people are looking for, but are somehow deriving some assumption about their “socio” part of “socioeconomic” status, as a non iOS user is perceived to be maybe “different” or “weird” in some way for not conforming and having an Android versus an iOS device.
I personally have never thought that, since I use Signal/WhatsApp/iMessage, and if you don’t have iMessage, I just use one of the other two, and I don’t care. But evidently, some people do.