There is a clear line of behavior that began with lying about crowd size and extended throughout the presidency, and yes a lot of it is driven by narcissism. It’s mostly not harmless though. A recent deadly example is how Trump supporters (speaking generally again) act concerning COVID. The president and his cohorts said “masks don’t matter, it’ll disappear soon anyway” for months and months, and his supporters believed it despite factual evidence, which has worsened the pandemic.
Tribalism is the word I was seeking, thank you.
Reading the thread again, I think you may be putting more weight on the use of “complete lunacy” than the poster intended. That was a reference to its parent post, which used the same words while taking “reality isn’t a point of view” out of context to mean “there is only one way to think about reality.” If there’s a straw man here, it’s all the way up there.
The response to "there can be more than one view of reality that is valid and true" isn't to respond with "lies are lies and using lies in place of truth is lunacy", (to paraphrase the parent comments, perhaps more fairly than the latter deserves) so to remain focused on "Alternative facts" is to be led astray by what amounts to a straw man. That whole debacle was a petty response by a narcissist to a petty narrative line by a media that isn't focused on what matters anyway and anyone repeating the White House line was more than likely acting tribally - as was anyone criticising the numbers. The proverbial storm in a teacup.
Regardless, who is arguing for "Alternative facts" here?