I'd write "As for a holiday <...> there aren't <...>."

'As' represents a function in this sense. 'Functioning as a holiday....' . Hope that helps

It is more like "Because it is a holiday that began over 50 years ago ..." or if want to use "because of" we could say: "Because of its status as a holiday that began over 50 years ago ..." I hope that helps.