This frustrates me all the time, but I am careful tight with money, so maybe IABU.
I come from a large family, and all of my siblings have been fairly successful money-wise. DH and I don't have loads of money but we are careful with it. We do own our house, and we go on holiday, but usually camping or similar in the U.K. most of our money goes on children's hobbies, and we save a bit each month, maybe £500 but that's only by not having coffees out or lunches out etc. The money is for university etc for our children.
My siblings often suggest joint gifts or joint holidays, which are much more than I would usually spend. They are nice about it, but I am always the one saying that it's more than I would choose to spend. In theory, I have enough money, but I don't want to spend that much. I don't mind if they go ahead without me, but they won't. Often someone will offer to pay my share, but I don't really want them to do that either. I know that I am probably being unreasonable, because what I want is for them to stop suggesting such expensive joint gifts, but that's unfair on them.
My DH never spends as much on his family. (We share all money, we don't have any separate money). Am I being unreasonable? I can't accept charity when We have money in savings, but those savings are important to us.