My adult sister

Just need to vent about my sister who is a year younger than I am. She is 24, didn’t finish school, has never worked a day in her life and doesn’t plan on getting a job anytime soon. She claims to have social anxiety but this is ridiculous. She refuses to go to the doctor because she doesn’t want to talk to the dr, she would want me to do it. My mom usually will take her and explains the issues. She won’t get a haircut because she doesn’t want to tell the hairstylist how to cut it. My mom has a lot to blame as she has babied her but I feel like this is extreme. She doesn’t know how to drive or cook. My mom isn’t in the best health and I’ve told my sister that I will never support her. So if something happens to mom, she’s on her own. It wouldn’t be fair to my husband to support an able person. Does anyone have someone like this in their life? I honestly fear for her future that she will one day be homeless.