>>86144978She thinks she's not very good at it, because first couple times she did it something always went wrong. So, if she can't perform perfectly, and couple people in the comments always bitch about it, it's better to not do at all. She sings because she wants people to praise her.
That's why Rissa doesn't do karaoke anymore. Meanwhile Liz does karaoke like 3 times a week. Liz sings because she just loves to sing.