In this meaning, fabulously is not just “very.” It paints a picture of huge money or luxury. People say fabulously rich, fabulously wealthy, fabulously expensive: so rich or so costly that it feels almost like a story. Magazines use it about film stars, palaces, and price tags that make ordinary people blink. It is colourful and a little glamorous — fine in features and chat, not a bank’s careful word. Though actually, the same adverb can mean “extremely” in a wider way (fabulously successful), but the sense you are learning here is the money-and-luxury one.

富得離譜地、貴得驚人地（專門用來形容極有錢或極奢華）