La Saint-Valentin est une fête du profit déguisée en fête de l'amour.
I am translating it as "for profit business" but fête in fête du profit might have some other cultural meaning for the French. Is there?
In the present age, when in matters of verbal expression an evident trend is a general instigation in the producing of pungent verbal forms, which results in the craving of numerous writers for a pun in their every sentence, the questionned sentence comes as no surprise, that is, no surprise in that sense that it is one more of those strained analogies without real pith in it. People are overdoing things under pressure and necessarily there must be an unavoidable crop of bad results.
What is meant, plainly, is that the celebration is a pretext for raking in profits; that is quite clear. The idea of celebration in this business of supplying some of the paraphernalia that goes with Valentine's Day corresponds to nothing ; there is no analogy ; the introduction of this idea is nothing else than a rather thoughtless, easy transposition, the pattern of which is nothing but popular. The activity has nothing to do with the rest of the business community, implies no ritual in the way of rejoycing about making profits.
A typical example
Vous parlez d'une direction communale des établissements de santé ! C'est une direction communale d'escrocs associés.
In the same way, here, there is no such controlling body. It must be said that serious thinkers do not indulge in that sort of rhetoric, it's just to easy, not refering to something specific enough.
If this particular practice is unique to the French language, of course the translation has to rely on a comparable context and is a problem; it could have, as is often enough the case, no real equivalent in English.
Irrespectively of a perfect correspondence of context, the following translation renders the idea fairly well, while exploiting a real parallel, as an overwhelming concern for making money without regard for anything else is figuratively represented as a worship of Mammon.