A rational approach would dictate that copyright laws protect the work, not the paper it's printed on. Therefore, your work is protected in electronic form. A person taking the electronic work and distributing it, be it for profit or not, would suffer just the same consequences as if it were published on paper. The problem really lies in the massive scope of the Internet. It crosses distances and borders in the blink of an eye.
Different countries have different laws and priorities.
To publish in such a vast arena of audiences is a decision that must be made by the author. I've heard paper publishers won't pay as much if a book has been published before. Right now, that's true with some publishers. It's understandable with the amount of money they must invest to publish a book. Eventually, it will become moot since there won't be paper publishers at some point in the future.