As far as I am concerned it is not dd's giftedness that brings problems, it is her physical disability and the fact that she is often ill and in pain. I worry far more about her brother who has the same disability but does not have her giftedness to compensate. If you are incapacitated for maybe 1/3 of your time you do need to believe you are brighter than other people to make up for it. It is harder to keep your courage up when you are also of average ability and feel you have no leeway.
Both of them are equally sociable and find no difficulty in adapting to different people; can't see any difference between them there, except that dd has a wider range, being able to talk to adults (and some of her peers) about grown-up topics, and with other peers and little brother about popular music and fashion.
Nor can I imagine a situation where dd wouldn't find enough to stimulate herself, with millions of books and over 6000 languages in the world. Not to mention the opportunities of learning instruments, composing your own music, writing your own stories, doing nature projects, chemical experiments etc- you'd need several lifetimes, even if in the best of health.
I believe gifted children, like non-gifted children, come with different personalities: some require almost constant stimulation, others prefer a more autonomous learning style. Dd has never been keen on my involvement, but leaving books lying around and dropping casual hints about what I enjoy works much better.
Also, it depends on you as a parent what you find tiring: I found dd much easier because I could talk to her as to an undergraduate from an early age; with ds I had to take the trouble to remember to explain things in simple language, and sometimes I had to explain twice (!), which I found much harder work. If you explain something to dd, it stays explained.
It is no doubt partly a question of personality, partly of resources- being an academic family probably helps, having a bit of spare cash certainly helps. Amazon is a godsend and charity shops are wonderful places. And living in a university town where interesting books end up in the Help the Aged shop (not like the hole I grew up in).