Just today I saw on a US based TV show that last year alone Americans spent $3.1 billion on flowers and greeting cards . 1.1 billion on greeting cards and remaining 2 billion on flowers. The host was encouraging people to rather donate that money to some sort of charity.
Honestly, Until few years ago I didn't know if such sort of days existed i.e. Father's , Mother's etc.
IMO, there are not many festivals/occasions in Christian religion so they have "made these up" . Now companies have started capitalizing on these by offering sales, specials and printing greeting cards etc.
YMMV.
This is what is called business..