Soo it’s nowhere near the same- but in FFXIV I once spent weeks after an expansion crafting/gathering to make money to buy a large housing plot. By the end of it I had around ~600million (an absurd amount). Unfortunately my luck just wasn’t here and I lost every lottery I entered. Now- I probably have like 5 million. Where did it all go? To other players. I’d just buy people things. Someone in chat said they really wanted this or that- I’d buy it. People wanted a small/medium plot and didn’t have the money? I’d give them the gil. I found literally no reason to have so much gil just for the sake of having it, and I love seeing people get excited. I’d put together little welcome packages with expensive mounts, minions, clothes, etc and gift them to new players. I kind of started doing this in real life to, just to a lesser degree as a stranger handing you a gift can be a bit weird. I’d like to imagine, with infinite wealth, I’d do the same thing to a larger scale- really find ways to improve and bring joy to the lives of others. I’d obviously spoil myself with things, but I imagine I’d spend most of it on other people.
I know you’ve said that you’ve asked her, and she’s stated she’s fine, but I think it matters how you ask. Sit down with her, mention the behaviors you’ve observed, explain how these things make you feel (I assume you’re worried about a friend), and just let her know you’re there for her if she ever wants to talk. Try not to make it too much about yourself, but be honest with your emotions… and try not to offer fixes for anything unless she asks. Myself and a lot of other women aren’t always open with men, even friends, because it can be exhausting dealing with their problem solver personalities; we normally know how to fix things already, but doesn’t mean they don’t weigh on our minds.