Luxury, nowadays, is ruinous. We criticize, but must conform, and superfluities in the end deprive us of necessities.
Le luxe absorbe tout: on le blâme, mais il faut l'imiter; et le superflu finit par priver du nécessaire.
Original text (French)
Notes from Wikiquote
Letter 104: La Marquise de Merteuil to Madame de Volanges. Trans. P.W.K. Stone (1961).