I'd point out to her how lucky she is to have somewhere to live, meals provided and a family around her. I'd make her watch some documentaries about how plenty of other people have to live, in shanty towns, in favellas etc. Plenty of kids share. I was in a dorm room. I didn't have my own room until I was 18. And no the other girls weren't always my age, as I got older I was put in a dorm with much much younger girls and was in charge of them and they weren't even siblings. It didn't kill me, it won't kill her. I'm not surprised you're upset, I would be. She's a very lucky girl and she could do with developing a sense of perspective abut the life that you've provided for her. I don't think some of the suggestions on here to give up your room are at all helpful. It's no wonder we're raising a generation of entitled kids when there is an attitude that the offspring's needs must be met before all others. It's like anything, if you're whole life was yachts. Michelin restaurants and the finest hotels, how much would you value those things? They wouldn't be in any way special. I value my own space now because it took time and effort to achieve it. It's just a life lesson she needs to learn and as she gets older and earns her own money and has her own kids I'm sure she will start to appreciate all you've done.
THIS
Op please don't consider moving onto a camp bed in the living room, that is nuts! She may want privacy that doesn't mean she NEEDS it.
There are many things we all and l am sure you, want but cannot have, ose this as a budgeting exercise, go through your income and expenditure and ask her to contribute her ideas and priorities, but explain that you make the final decision.
Personally l agree trips and holidays make fantastic memories, and your house sounds fine.
I had to share with my brother until the age of 8, then had a really tiny room, barely room for a single bed and tiny wardrobe with an ill fitting door, no privacy there, but l was aware, my very hard working parents couldn't afford a larger house so never complained, l would have had a very sharp reply had l dared to!!
I now live in a large house and appreciate it every day.