"Maybe my real problem is that I take myself too seriously—from my perspective, that other people don't take themselves seriously enough. Like I'm off in my corner going mad, unable to comprehend why, why doesn't the world understand that words mean things. But when you actually talk to people, their anticipations of experience are all just about as well-calibrated as mine; they're just really bizarrely cavalier about using words to mean whatever they feel like at the moment."
"So basically you're going mad over ... prescriptivism."
"I know, usually I'm not the type to get into linguistic prescriptivism debates, but I guess I had assumed that those were always about obscure things, like when to use comprised instead of composed. I wasn't expecting people to redefine a top-20 noun out from under my feet."
"And yet!"
That's a difference of values. You want words to have fixed meanings because that way it is easier to explain how the world is. But they are interested in other things, not in explaining how the world is, and their ends are better achieved by using words to mean whatever they feel like at the moment.
That also explains why you find this upsetting: you want people to share your values, but they don't, and they won't.
Well that's disingenuous as all hell.
I think entirelyuseless has a point ... although there are social agreements (e.g language), social agreements are often fluid and changing (as well as not always fully agreed upon).
A further reflection beyond the nature of social agreements is why we as individuals need that certainty ... is it basic insecuity in an uncertain world? If yes, then how is the individual supposed to cope? Is it with age that we eventually figure out the appropriate set of compromises?