Eh, actually there are arguments to be made for the employer being entitled to a share of the value, yes.
They provide the materials, the tools and machinery, the designs that are being made (assuming some sort of manufacturing company for this example). They also carry the risk (unless of course they are a corporation, the ridiculous entity created to reap the advantages of personhood while avoiding all its responsibilities and drawbacks).
So, a slice of the pizza should be for them, but certainly not 7/8.