He lost 0.58 so nothing major, he can still see the balance on the blockchain so he no doubt he'll be watching that balance grow in the future, he remembers it was worth around $110 at the time.
.58
BTC? its worth 10x by now if his initial investment is $110. And just like what others have said, you need your private keys to retrieved your friends bitcoin. I also have lost bitcoins in the past, and the only thing that cheers me up is that I can earn that bitcoin back. It will took me months though to be able to at least break even with my investment.