I truly believe there were only 2 factors that mattered in its death. First and foremost was the massive amount of debt the failure of the Saturn had left Sega already trying to recover from. If they hadn't had that to worry about it would have been financially successful as it stood.

The second factor was more insidious. Sony did such a good job hyping up the PS2 that people really believed it would be way more powerful than the DC. Yet the DC could produce better graphics than the PS2 at launch. But that's not what the public perception was. I worked at Electronic's Boutique during the PS2's launch, and no matter how much I tried it was impossible to diffuse the hype around it when I would try to convince people there was no need to wait and they should get a Dreamcast today rather than waiting for the PS2. But it was a lost cause most of the time. And ultimately those people are better off with how things eventually played out