"You are getting rich."
Translation:Vous devenez riches.
They're very similar but not quite the same. I'm no linguist but "become" instead of "are getting" implies a different context. Almost a different tense. It's as though the adjective has just begun, or happened presently:
If you "are getting" rich, it's happening over a period of time.
If you "become" rich it implies something sudden. Like "You become aware". While technically there's nothing incorrect about the sentence, it's something you'd almost never encounter in actual conversation or writing.