I find this so strange. If you don’t celebrate it, then that’s fine. Nobody is trying to make you.
However, some of us do celebrate it. And we enjoy it. So, why be rude about it? Why all the vitriol? Every year, multiple threads of people being remarkably unpleasant that others have the effrontery to celebrate something that they don’t personally care for. Why?!
And the ‘it’s commercial nonsense’ and ‘we celebrate our love every day’ arguments aren’t relevant here, as I’m not asking why you don’t celebrate Valentine’s Day (your relationship is entirely your business), I’m specifically asking why some people are rude about other people celebrating it.