No it is not (at least, this of course depends on national laws, but I guess it's pretty much the same in every country).
Quite easy: when you buy the disc, you buy the rights to play that disc etc. Making a backup of that disc may be legal as well. But... thing is that when you sell your disc, you also sell those rights to the new owner. So you don't have the rights anymore to own the backup.
Welcome aboard btw...!