I guess that there is nothing any Bitcoin holder can do when they lose their coins, they have to accept the lose as a donation to the Bitcoin community, although no other holder can benefit directly from the "donation. That means that anybody that wants to hold Bitcoin must have sufficient knowledge about the importance of securing their private keys otherwise the inevitable of losing their coins permanently will happen and their only consolation is that they have donated it. I think that this is one of the major demerits of Bitcoin because aside from a holder losing his/her private keys, death, lose of memory, man made and natural disasters can also cause permanent lose because Bitcoin is not centralized, except the person shared the private keys with a trusted person or people.