My younger brother and I used to have a PS2 about ten years back until we got a 360, after which we decided we no longer needed and would never again need the playstation, only the xbox (we were young and knew very little about gaming or the internet) and wanted to sell it. I eventually came back around and we never did anything, but it slipped my mind until a couple months ago, when I chose to dig the playstation back out and use it again.
Whenever I brought it up with my brother, he got unusually evasive and vague about it, bringing up all kinds of excuses as to why I should stop looking for the playstation. Eventually, I wore him down enough to tell me that he had gotten rid of it at some point without telling anyone. Obviously, I was pissed (though I somewhat suspected he didn't have it due to his persistence that I drop the topic and how much longer than usual it took me to break him), but there wasn't anything I could do. Fortunately, my grandparents have a PS2 they'll let me have, I found a couple of our memory cards while cleaning, and I still have our copy of Star Wars: Battlefront 2, so it's not all bad.
However, I'm not 100% certain if he truly got rid of it or just said he did to make me shut up (knowing my brother, I could maybe see it go both ways), and I've no clue what happened to our game collection - admittedly, most of them were movie tie-ins, but we had an original copy of one of the Myst games plus GTA 3.