I read somewhere, and forget where, but most probably from Super Power, Spoony Bards, and Silverware (https://mitpress.mit.edu/books/super-power-spoony-bards-and-...), that Sega never had large margins with their home systems, unlike Nintendo. When the Dreamcast had an underwhelming initial release, due to their cooled reputation, they simply didn't have the money to keep investing in the system to try and turn it around.