Because of a curse Athena put on her.
There is no proof that Medusa could not help but to turn people to stone.
Medusa could turn people into stone.
Medusa can turn people who meet her eyes into stone.
Medusa
When someone looks at Medusa they turn in to stone.
Medusa didn't "want" to do that; it was her nature.
no she turn them to stone
turn people to stone
turn people to stone
Turning people to stone
turn people to stone
Turning people to stone