In March 1938, Jerry Siegel and Joe Shuster signed a contract transferring the rights of their character Superman to Detective Comics, Inc. In return, they received $130 - split between them, so $65 each.

Superman went on to become one of the most lucrative fictional characters in history, and Siegel, by the mid-1970s, was working as a typist in the mailroom of the Los Angeles Public Utilities Commission and living in a 1-room flat.

This is not an edge case. This is a foundational story of how American comics worked for the first four decades of its existence.. and, in some cases, considerably longer than that.