Appeasing foreign powers. They thought that they would eventually stop asking for more after they were given enough, but as we know it today, hitlers only plan was expansion across all of Europe.
They don't teach it enough perhaps ?
The bridge "rose" from the ocean as vast amounts of ocean water became tied up in the enormous glaciers of the last ice age. That exposed the broad continental shelves now covered by the Bering Strait and created the land bridge. The bridge last arose around 70,000 years ago.
Economic hardship and distrust of Virginia colonists who were unable to acquire land