Yep, it started a while back, but even in wikipedia...
"Since the 19th century, handwritten notes have largely given way to mass-produced greeting cards.[4] The mid-nineteenth century Valentine's Day trade was a harbinger of further commercialised holidays in the United States to follow.[5]
In the second half of the twentieth century, the practice of exchanging cards was extended to all manner of gifts in the United States, usually from a man to a woman.Such gifts typically include roses and chocolates packed in a red satin, heart-shaped box. In the 1980s, the diamond industry began to promote Valentine's Day as an occasion for giving jewellery."
But you're right, the return on investment can be well worth it
