Peter continues on the example of the destruction of the cities of the plain by mentioning that God "delivered just Lot, vexed with the filthy conversation of the wicked: (For that righteous man dwelling among them, in seeing and hearing, vexed his righteous soul from day to day with their unlawful deeds;)..." Peter goes on to say the point of mentioning Lot in the next verse. But many observations can be made from Lot's life. Lot should have never been in that position in the first place because God told Abraham to get away from his father's house (Gen. 12:1), and Abraham disobeyed (Gen. 12:5). Yet Lot was selfish in choosing that land and chose to pitch his tent toward a city he knew was wicked (Gen. 13:11-12). Then he moves in (Gen. 14:12) and gets involved in city affairs (Gen. 19:1). He is "tormented" by the conduct of the people he dwells among. But he is also affected by it, so much so that he is willing to throw his virgin daughters to the men of the city (Gen. 19:8). They are obviously affected by their treatment and all they see too (Gen. 19:30-38). But Lot is still righteous, a believer, though a backslidden one.
The application: Unless God calls us to a place of sinners, we ought not to choose to be among sin. It will always bring us down. It will affect our entire family. Lot loses his older daughters and son-in-laws (Gen. 19:14), his wife (Gen. 19:26), and basically his daughters. Their actions create two long-term enemies of Israel. Yet God will save and even hear a backslidden Christian. Lot asks for a city to be saved, and it is (Gen. 19:17-22). But the consequences seen make that lifestyle not worth it.