My dd is in the lower years there. I’d say she’s the opposite of ambitious and thick-skinned! She is quietly confident, determined - very much a self-starter. Another thread, a while ago, described the type of girl who thrives there as the sort who never had to learn their times tables at primary school, aced their SATs without really trying, can easily learn 20 new bits of French vocab on the tube home after a netball match, then do a quick bit of maths homework and finish off with some online debating for fun - and enjoy all of them, for the intellectual stimulation. Which is sort of what SparklySnake said, too.
I think, weirdly, coming from a state primary helped. We told her she’d be with lots of girls cleverer than her, that she’d have to work hard, that it would be very different. As it turns out, she loves the pace, the breadth and depth of the lessons, the music and drama opportunities etc and she doesn’t have any trouble at all keeping up while still doing hours of outside school activities.
On finances, I have no idea. Dd has been to a few friends houses (pre lockdown) but I never have, and not even dropped / picked up as she takes herself by tube. It’s just not a subject that has come up in her friendship group, other than in the context of ‘going to x country this holiday to visit granny’.