Well no, unless you are taking a risk. The reason the employer/client pays upfront is because they take the risk and you would get the cash upfront with no cost

Well no, unless you are taking a risk. The reason the employer/client pays upfront is because they take the risk and you would get the cash upfront with no cost if there is a downside/i.e it fails. Unless you propose something where you take nothing upfront and then it comes from the revenue. But then again its about where the risk is, so if they have virtually guaranteed revenue then there is no risk taken and hence no reason to share the upside. In short: More risk = More upside, otherwise the salary/fee is capped.