Lord Voldemort cursed himself.
Ever since he found out about horcruxes, he had been so sure that he had stumbled upon the ideal solution to cheat death.
In his zeal to ensure his immortality, he had created five of those – even before he heard part of the prophecy that foretold the advent of his nemesis.
The moment his rebounded killing curse struck his body Lord Voldemort fell over dead, never to be resurrected.
It is true, that the horcruxes ensured his continued existence; the problem was that it turned him into a ghost.
He had thought, that with his soul anchored into this "plane of existence", he could roam around as a wraith of sorts, waiting for his eventual resurrection. All his emergency plans were based on this assumption.
He had been wrong! He was a ghost now and there was nothing he could do to regain a body!
..he really shouldn't have put so much faith into an unprovable assumption and put all his eggs into one basket..
In hindsight it was so clear to him..
No wonder there were so few ghosts; the few who remained as ghosts were those that had bound their souls via horcruxes.
And while some of the other ghosts may "move on" over the years, seeing as their soul containers were destroyed by accidents, he had been so intelligent to create five of those foul things.
Lord Voldemort would continue cursing himself for a very long time.