Boeing built an inherently unstable aircraft in multiple regimes in a rush to compete with airbus. They started out thinking there was one regime, and discovered (like we always joked about the Beech 1900 guy that came back in saying we need more fins) that it was way worse than anticipated.
It was not fly by wire to make it stable, but instead a hacked analog patch with a single point of failure for an aggressive correction for said instabilities.
What did you think would happen???