Kvod haRav, A man anonymously steals 10 bitcoins worth $10k from his victim and holds them for a year. During that time they increase in value greatly to $80k total value before falling to only $5k in total value. Since they are not worth much anymore, the thief returns the same 10 bitcoins (guilty conscience). The original owner lost the opportunity to cash them in for a huge gain, AND he lost the use of whatever money he would have gotten. Is the thief free and clear since he returned all the original coins or does he owe? How much would he owe?

Asked on May 3, 2021