Actors do it all the time - pretend to be somebody else. That's what ghostwriting is, but with anonymity added.
Some people don't understand why anyone would want to be a ghostwriter. They would say 'But you do all the hard work and someone else gets the credit.' This is true, but a ghostwriter gets the juicy paycheck at the end of the job and doesn't have to do any of the tedious stuff, like marketing the book, attending book signings, arranging interviews etc. And fame isn't for everyone.
In fact, in my view, ghostwriting is a very attractive profession. It gives a writer a chance to write in a genre that maybe they wouldn't consider doing under their own name. They may get to meet interesting people, all with fascinating stories to tell. They get to write with someone else's 'voice' and thereby improve their own writing ability.
For the writer, ghostwriting has to be a win/win situation.
I am a Copywriter, Proofreader, Virtual Secretary and Author.