I think of my wife and myself as extroverts and we do have a very large social circle. Still we don’t host as often as we wanted, maybe once every two months. One of the reasons is it can get very expensive. The last party we threw was a Sunday brunch for about 15 adults and a handful of kids, and we spent over $500 just in pastries. People still bring stuff but we don’t expect them to. Dinner can get even more expensive particularly if you cook meat dishes these days. Then all the time it takes which also translates into money. To host a dinner party it takes me part of the week shopping and the entire weekend cooking and organizing. So most times is better just to call a couple of friends and go out to a restaurant.

Eh, in this economy I think it's fine to request contribution, either material or monetary. Also once every two months or so is pretty decent, cheers to you