What prompted Avraham to move his tent?
Rashi #1 and Seforno (by assunption): Since the four major towns no longer existed, no more travelers passed his tent. 1
Rashi #2: To distance himself from Lot, about whom rumors were spreading that he had had relations with his daughters. 2
The Seforno adds that Avraham set up tent between two big towns, in order to attract travelers from both towns, in order to spread the service of Hashem. Moreover, it was the location of the well mentioned in Bereishis 16:14 (Rashi in Bereishis 24:62).