What does Genesis 19:18 mean?

In the previous verses, two angels have forcibly removed Lot and his family from Sodom to save them from God's impending judgment on the city. As predicted by God, there are not even ten righteous people left in the entire city, and Lot and his family have recently been rescued from a mob intent on raping their travelling guests. These strangers, the angels sent by God, then told Lot and his family directly, to run for the hills to save their own lives. They are not to look back, not to stop in the valley, or else they'll be swept away with the citizens of Sodom.

Now Lot responds by complaining and criticizing the angels' plan. For whatever reason, Lot does not think he can make it to the hills, and will instead ask to stop in a smaller town outside of Sodom, called Zoar. Lot continues come across as less and less likable and grateful. Still, the Lord will continue to be more and more merciful to him.