The saying is "eat the rich" because "kill the rich" would get you banned from social media, yet eat implies cannibalism and is thus more offensive.

Eat the rich existed long before social media

TIL, but I still think it took off in the social media era in place of other phrases because it doesn't directly suggest violence.
- Something about when all else is gone and the world is in chaos, eat rhe rich because you can't eat money. There was an original quote I can't reacall exactly but it's to that effect.
- https://en.wikipedia.org/wiki/Eat_the_Rich_(Aerosmith_song)?wprov=sfla1 was popular before social media, it's like saying "groovy" got popular because of influencers.

Not a social media thing. The original quote goes:

Rousseau, who was also one of the people, said: 'When the people shall have nothing more to eat, they will eat the rich.'

Cover of Aerosmith's Eat The Rich

Which is hilarious because Aerosmith are now the rich that we'd be eating.
- lol no they aren't. I get the impression you're pretty inexperienced given your responses in this post.
  
  Aerosmith, collectively, hasn't got enough to throw at something to make it do what they want it to. They have maybe a few hundred million all put together. Bezos, Musk, even Trump who exists on credit and grifting can and do do that. It's those kind of people (and I use the term "people" loosely) that the saying is directed at.