Repost: Why is she doing this? Self esteem issue?

My good friend Hannah is currently obsessed with meeting random people on the Internet (if you've read my other question, you probably know most of the story.) Anyway, she poses as a 19 year old Dutch girl when really, she's only 15 and she lives here in Canada. She even made up a fake MSN account and used Google Images as profile pictures. She chats with guys from around the world, pretending she's this girl instead of hanging out with her real-life friends. I was just wondering, what's the reason she's doing this? Is it a self-esteem problem? She doesn't have much confidence and not very many friends besides myself and about three mutual friends. I've been trying to get her to stop playing this Internet charade, but she won't, and she won't tell me why she's doing it, just saying "It's none of your business."