Why would drug addicted, insane relatives think you'd want to drive 500 miles for a visit?

As some of you know, I have two daughters. One is an absolute blessing. A giving, caring, funny, hard working jewel. Her older sister is a drug addict who is nasty, accusatory, certified a Neglectful Mother by CPS (he’s grown now) , aggressive and threatening yet she is insulted I don’t want to drive five hundred miles to visit her! She scares me! I think she just wants a hand out but I’m not sure. Would you like to visit her for a couple days? I offered to pay for drug counseling and got told off.