Look at it this way:
If you have all the ingredients, you can bake a pie..
If you have a pie, you can't take it apart to get the ingredients again.
This is probably not 100% true for any computerprogram, but it comes close.
One big advantage is you can make something without having to worry every Tom, Dick or Harry steals your code and/or graphics.
I told my dentist I had trouble with my teeth and asked her to fix it without looking in my mouth..