Can’t they discover the world beyond? Weren’t they humans; don’t they have the mind to move on and focus on something else, since trauma and grief will run its course, sooner or later, and not just haunt the living?
If I were a ghost, I’d be tired of acting like one… even if I was murdered or otherwise died untimely
With the exception of Casper the Ghost, I don’t think I’ve seen the alternative take on it
This presupposes ghosts do exist, though I believe ye skeptics would tell me no, which, alright, you win the argument
Disclaimer that I don’t believe in ghosts, but in fiction at least, I think the usual implication is that a ghost is someone who hasn’t passed on correctly. A few people have brought up unfinished business already, but even in stories that don’t bring that up, ghosts are often people who died horribly, prematurely, and/or violently. Sometimes they’re explicitly under a curse keeping them from moving on.
Basically, the circumstances of their existence are wrong, and they’re stuck due to forces beyond their control. That’s kind of the tragedy of being a ghost; they’re often a whittled-down, corrupted version of their living self.