If you want full value (which might be zero or negative at times) for your labor, you should start your own thing and keep 100% of the value you create.
If my employer wasn't making at least 3x (and ideally more like 5x) the total cost they were spending on me, I'd start worrying about the stability and longevity of that relationship. (So far, very happily employed there almost 13 years and no end in sight.)