It is if you are hosting; but if you are going to the party...hey, it's free food! I think a systematic analysis would show that it would be cheaper for all of us on the whole to share food at parties since it is cheaper to buy in bulk.

A lot of parties have always been pitch-in or BYOB.

I was going to disagree but then realized I now shell out at least $100 when two families and their kids show up for 3-4 pizzas with toppings and chips and dip and some juices.

And god forbid I try and provide fresh fruit and beverages on that budget…

A fifth of vodka has been like $15 for at least a decade otoh