I'm not a huge fan of celebraties giving speeches on stuttering. The wiring in your brain that makes you stutter is completely different and unique for everyone. Some people can speak fluently through techniques and therapy, some will never be able to speak fluently. Ed Sheeran was able to overcome his stutter using rap, but the way his stutter is wired let's him do that. Same with Steve Harvey. He is by no means a doctor of any type, but he preached that reading a book in the mirror and thinking about what you want to say 3 times before you say it will cure you. Those who stuttered and still became actors/actresses are the ones who were able to cure themselves, and so they assume everyone is like them.