Why do people buy used or refurbished iPhones?

[NoFunForMyLife]

Why do people buy used or refurbished iPhones since the FaceID parts may be aftermarket or third party and not have the original and genuine FaceID parts? Wouldn’t that be unsafe and cause injury to your eyes and skin? How are the people all over the world that use refurbished or used iPhones not blind since if the FaceID parts are aftermarket, it could damage their eyes, especially if they use the device unknowingly day to day and didn’t know the FaceID parts were not the original and genuine ones?