We live in what I think is the most self obsessed, narcissistic time ever.
There's a lot of people who would rather wallow in nothing than try for mediocrity.
This younger generation has, unfortunately, their eyes on the most inflated lifestyles possible since the day they were born, live in relative comfort, and want wealth and fame for nothing.
This isn't some child from a struggling home. She went to a private Christian school. She went to art school. These are expensive endeavors that rarely pay off. She sounds like she was on the autism spectrum but "highly functional" often means that significant impairments are few. She came out as "trans" rather late....and while we can attribute that to her Christian upbringing, we shouldn't, because the number of otherwise gay women coming out as "trans" recently is not small. It could have been a fleeting phase or something struggled with lifelong.
We can never know, because we the public aren't allowed to read manifestos anymore (something I used to do just to gain some insight into these and various other cases). Regardless, she had something to say....and probably felt like shooting the school up would get it said. Perhaps bits and fragments are somewhere online, perhaps not.
It's just a tragedy now, motive a mystery, solutions impossible. I'm sure we'll hear some narrative curated version of what it was about from one side or the other but it's all going to be just that....politically motivated tripe.