2. The market moved in a different direction from the one we expected.
3. We were trying to do it without the kinds of connections we needed to get funding.
4. We stuck at it too long, such that we were considered "too old" by the time it was mature.
5. Our product would improve user's lives but only with a highish startup cost -- some of which we could have mitigated, some of which we couldn't.
6. We had no idea what we were doing.
7. The dotcom crash reduced access even if we had known what we were doing.
8. We had no idea what we were doing.