I mean, if more than half of adults can't read past a 6th grade level-which is absolutely something that I'm gonna need a linked source for- what could possibly be causing a trend of low reading comprehension?

It's not because those people are stupid and only 46% of people are "smart". It's probably a multifaceted issue that probably has a lot to do with what education policies have been in place and poverty rates. Or maybe we don't teach reading in a way that catches 54% of students.

This whole "the people are dumb but not me" thing is just a dangerous assumption that I see paraded around like some silly ass humble brag.

Look at the numbers, if something literally doesn't work for more than half the population you do not get to point and call them stupid while patting yourself on the back for having better opportunities.