Comics creators are famously exploited. Superman's creators died in poverty, and most work by Marvel and DC is performed as "work for hire", i.e. not generating royalties for actual authors. This is also why authors increasingly try to publish independently, but that also means working on brand new series that may or may not attract any popularity and actually generate profits. For one Mark Millar or Todd McFarlane there are hundreds faring worse than Joe Shuster.
