it's all manufactured image. she is doing what her handlers tell her to.
Miley has zero actual vocal or acting talent, so she's going for the tabloids and clickbait approach to remaining a relevant famous person. If she didn't act apeshit crazy, her career would have tanked in six months.
The real question is why. She's got enough money from Hannah Montana to fund a private army to conquer half of Africa. She aught to get a ranch on the outskirts of Nashville and start a charity for sick horses like every other rich washed up singer.