Why would most people rip someone off for drugs but would return a wallet they found

I'm guessing that the people who would rip off someone for drugs, wouldn't return a wallet either. Unless there was no money in it and they were hoping for a reward.

They can't smoke or snort the wallet.

Guilt ?

The addiction of drugs is stronger than their morals. Simple.

Stealing from other criminals is just part of the game

Uhm coz they’re dope fiends