No she didn't choose to he born, but that is true of all of us! It will probably help the OP to move out and develop a bit of independence.
And, tbh, if my adult child chose to work compressed hours so they could sit around the house for 3 days a week instead of 2, I'd be worried about them. Maybe her parents are too. Maybe they wonder why this is all she wants for herself. Maybe they haven't articulated it well. Maybe they're a family who don't communicate well. There are many possible explanations.
The OP has described them as furious but if she hasn't grown up in abuse and is just a bit entitled and immature, then I wouldn't necessarily accept her interpretation of her parents reaction as reliable either.
The only people I know who've grown up in abusive homes wanted to get out as soon as possible or at least spend as little time there as possible. Not increase the amount of time they spend there.
It's not that I can't see the point in what you're saying, just that I'm not convinced it applies here.
I understand that it's more difficult nowadays for young adult children to leave home - I have two of my own and have always told them theyd have a home with me for as long as they needed it. I've also seen the impact that living at home for longer has had on some of them and its not always positive.
I can think of several examples where the young adults (20somethings) have thrived and seen their mental health improve dramatically once they lived their lives as independent adults and not teenagers. Some lived at home as independent adults and more like lodgers. They fared a lot better than the ones who just lived as teenagers.
I don't think the OP is going to return so I don't think she has some great tale of abuse to share. But I think it's interesting as part of a wider discussion on MH and just growing up and independence too and the impact on these of adult children having to live at home for longer.
I love my children and they're my favourite people. But, as much as I'd have been happy for them to live at home for as long as they needed, I also want so much more for them. And I would have been frustrated in the OP's parents position if they didn't have a little bit more oomph about them. And then considered going nc the second they didn't get their own way about something.