Were they not compensated for their time when they did the work? If I, as a web engineer, help create the next facebook for someone and I'm paid my wage during

Were they not compensated for their time when they did the work? If I, as a web engineer, help create the next facebook for someone and I'm paid my wage during the time, and this new facebook somehow obsoletes me, are you saying I should be entitled to gain more from that, even though I was already paid what I agreed to be paid when the work was done?