Has the highest income users of the major social platforms - and very few poor people 
Discussion
What qualifies as "high income" here?
That’s a good question- it’s likely in the article
“Additionally, 44% of LinkedIn users take home more than $75,000 per year, which is above the national median in the US.”
Guessing 6 figs
But it’s also the absence of poor people - but just the presence of rich
I wouldn't necessarily consider 75k/low 6 figs to be rich automatically (though the latter has the potential to become rich over time) but I think it'd be better to reframe it as presence of the domesticated/white-collar middle class. The type of people who had a cushy upbringing and went the traditional route (going through uni and then getting a desk job at a large corpo) in life without questioning the world around them.
I don't mean to be overly harsh in my description- I come from a similar background myself
unrelated: Really wish there was a way to edit notes, I hate posting something and noticing grammar mistakes a few minutes later