WHY DOES MY USB SUPERDRIVE KEEP BREAKING????

Hi guys!! I'm back.

so a little while ago I posted about having trouble with my superdrive, Apple were kind enough to replace it under warranty. I recently bought a Mac Book Pro, and kept the replaced USB superdrive. It didn't work, and hasn't worked since I got my new Macbook pro. I thought for so long that something was wrong with my computer, because surely after having my superdrive replaced, it wouldn't be it. But today I have realised that it is indeed the superdrive that is broken as it ejects any DVD that I put in! At first I thought it was a transfer problem, as everything off my old mac was sync over (the same as last time). But my question is... WHY does it keep breaking??? I find it so strange. I take good care of it and put it in a hard cover when i'm not using it. The cord is still in tacked and all the wires etc in the tip are all in good condition. I just don't understand. also, will this one still be under warranty? Because if not I won't bother replacing it, considering it will probably break in 2 months time.