She doesn't care. She'll pretend to care, if she's trying to garner sympathy but she really doesn't. Several times she has cynically thrown out there that "everybody dies." She has also said she knows she won't live to 60 (or was it 50, even?) I don't think it's false bravado I think she really doesn't care that she's not going to live to old age and I also don't think she cares that her life is so empty. As long as she has food and attention she's good.
She's just betting on dying painlessly in her sleep I guess? I'm sure she's afraid of suffering a serious complication from her obesity like stroke or beetus amputation. Not afraid enough to do anything about it apparently.