If someone wishes me "Happy Thanksgiving" in public, then I will say the same back to them. But I've decided to not be the one to initiate those words in writing or out loud.
The underlying reason for the Thanksgiving holiday is beautiful: sharing a day of gratitude with those we love.
Two years ago, I was busily sending a copy/paste message to writing friends I'd met through Twitter. I realized, after I couldn't delete the message, that I'd wished Happy Thanksgiving to a Native American friend. Fortunately for me, she was patient with me, saying that she doesn't observe the holiday and that she makes a practice each day to have gratitude.
I believe there's other reasons for refraining for wishing "Happy Thanksgiving" to people we don't know that well.
On the surface, this holiday has become synonymous with elaborate food preparation and feasts. Some folks may find this a financial strain? Choosing between utilities, medications, and holiday meals.
Some folks may be apart from family or friends, feeling alone. If we wish them this greeting without knowing their plans, then doesn't it become an empty, even thoughtless, greeting?
This might be applicable to other holidays as well? Just something to think about. I share these thoughts with you and welcome your thoughts and ideas on this as well.