Mostly it’s just people discussing whether flour should be measured by mass or volume. Jokes about using some mcburgers per football field -esque satirical units, some joke about using moles instead. Some comment about a funny misspelling in the meme. Nobody is flying into an incoherent rage.
A person can be rich in many ways. A coral reef is rich in biodiversity etc.
The rich refers to the group of people who are financially rich to an obscene extent.