1. He started the leading software company in the world. He’s not just a little rich—he’s filthy rich !
2. Whenever I buy a lottery ticket, I dream about what I would buy if I were filthy rich

Antonym: flat broke. This expression arose from the idea that money was “filthy,” or dirty. For some people, the idiom still carries a negative connotation. But for others, to be filthy rich is a dream.