Back in the land, the herds are too large to share pasture, and Abram — the elder, with every cultural right to choose first — gives the choice away to Lot. Where does that generosity come from? From the promise itself. A man who believes the whole land is already his by God's word can afford to release his claim on the best of it. Lot chooses by sight, toward the Jordan plain, "like the garden of the LORD... like the land of Egypt" — and both comparisons are quiet warnings, because Eden is lost and Egypt is bondage.
Watch the drift across the next several chapters: he pitches his tent toward Sodom here, he's living in it by chapter fourteen, and by chapter nineteen he's sitting in the gate — a city official. That's how compromise moves. Toward, then in, then of. And yet 2 Peter 2 will still call him "righteous," vexed by the city's filth even while embedded in it. Hold both of those truths; the text does.