I know you trot out this 'joke' periodically (last seen on 8 Oct) but it really isn't very amusing.
If on this occassion you were trying to use it as a serious point I would tell you that not everyone wants to fly from A to B. Many people want to fly from C to D, and if that route is viable Ryanair will open it up. It will only be viable if people choose to buy tickets to fly on it. So, the relative proximity of A to C and B to D is pretty irrelevant. FR successfully operate many routes which simply didn't exist before. As always the bottom line is, if you don't like it don't buy tickets for it (sit on an internet forum and make tired old wisecracks instead).