What is the comparison to those who seek unjust gain?
Rashi: They steal coveted matters, and think that they are for free.
R. Yonah: They see the pleasure of unjust gain, and forget the judgment and recompense.
Malbim: All of them set a trap for one who is enticed like a dove to be caught in the trap. It seems to [the victim] that he is being given wealth for free.
Why does it say "Es Nefesh Ba'alav Yikach"?
Rashi, from Bava Kama 119a #1: Hashem will take the (thief's i.e. the) current owner's soul. R. Yonah - sometimes the thief will be punished with Misah bi'Ydei Shamayim, based on the pain and damage to the victim - "Mah Tikvas Chanef Ki Yivtza Ki Yishal Eloka Nafsho" (Iyov 27:8) - the thief's soul [will be removed].
Bava Kama 119a #2: Hashem will avenge the thief, i.e. for he mortally afflicts his victims.
R. Yonah: Chazal said that this refers to Dor ha'Mabul. Their decree was sealed due to theft.
Malbim: When they will see that you have wealth, they will kill you and steal it from you - "they are quick to spill blood" (16). This danger is clear; from here, he will teach to his son to guard from all enticements of sinners.
