You don't have to be Irish to drink beer on St. Patrick or you can decorate a Christmas tree without the need to be a Bible licker, same as that you can feast on Mexican or quasi-Mexican food on Cinco de Mayo.
Discussion
You're mixing up cultural appreciation with historical meaning.
Eating tacos or putting up a tree is fine, but turning a foreign military event into a drinking holiday and pretending it’s part of your own history is a different thing.
Celebrating without understanding is how culture gets dumbed down and stripped of meaning.