The whole body of contract law stands in contradiction of your assertion. We also privilege facts and verifiable events in history and science, notwithstanding the existence of bullshit. I don't share your fatalistic view, not least because any undertaking whatsoever could theoretically be dismissed with the more-or-less similar argument of 'well we're all going to die, so what's the point?'

I agree with you that much of society is based on based on bullshit, but not that it's pointless to do anything about it. I used to smoke cigarettes but gave them up because they were making me feel bad. While I have most likely shorten my life by the time I did spend smoking and won't be able to recover that lost time, I still cared enough about the quality of life that was available to not want to shorten it further. Likewise, insofar as bullshit deems to be destructive of trust and social relations, I'm arguing that we would be better off with less of it.