I don’t think your DD is being a diva or entitled. I think that’s a bit harsh.
I think you are being U to directly compare your experience with your DD’s. For example, you wrote that because you didn’t wear retainers (for whatever reason), your teeth are only a bit better than they were, and because you can now afford to, you’ve decided to get aligners. This is nothing to do with your DD - only your own circumstances and your own choices.
From what you’ve written, presumably your DD is a teenager and at school, so she is not working and therefore not earning any money, so she can’t fund her own dental treatment. Of course she’ll find it unfair and not nice that you are in a position to straighten your teeth but that she can’t have the same privilege.
Is there are any chance you could afford braces for your DD? I know they’re very expensive. I completely understand. But it will help with the general health of her teeth.
You mention she has overcrowded teeth, which is not just a cosmetic issue but also a health issue, as it may be difficult for her to clean her teeth properly. It may also get worse as she gets older. When I was a teenager,
I had braces on the NHS, which was great, but they only gave me a retainer for my top teeth as they said people would only see my top teeth anyway (when I smile).
Over time, my bottom teeth become more and more crowded, which made it really difficult to eat and to clean them.
I’ve now got Invisalign, similar to you, and it has been amazing. So helpful. It is very expensive, but it has been fantastic for the general health of my teeth and my confidence.
If there’s any way you are able to get braces for your DD, I reckon you should consider it. She will thank you.