Is she insecure? Does she think that being herself isn't good enough? Is it a way of getting away with things she wants to do, because she can blame it on her alter-egos? Is it just artistic expression?
But to answer your question. No she doesn't. Especially since she killed her alter ego and then went on to release her two best and artistically creative albums to date.
It's just a way to show different sides of herself. She said in an interview that all her alter egos are part of her.
Also she's not the first nor the only one with alter egos. I don't know why you are singling her out.
Everyone knows "Sasha fierce" is beyonces stage persona.
It's what helped her to originally go out and .kill it on stage,
It isn't just there like roman.
People are counting:
Yoncé (extremely sexual)
Third Ward Trill (gangsta rapper)
Miss Third Ward (pageant queen)
BB Homemaker (housewife)
Honey B (Gaga's bff)
It's so dumb