I didn't even imply that, the reality is that many of us bought what we thought were great domain names with the intention of developing them, however the actual reality is that many of us have never, and never will, get around to developing them.
Why do we keep hold of them? Quite simply to stop someone else developing a site on that name. Typos and name protection are another thing altogether and, as I wrote, url forward or create a splash page...simple, just do something with it!
I have relinquished 200+ names during the last couple of years and I have never bothered to look if anyone has registered them, I don't care, I over-estimated my ability to use them plus, honestly, I have never needed them.
And I'm just about to let another 30-40 names die this next month or so.