even if we accept that ghosts are real (and there's not really enough evidence to do that), it doesn't suggest that there is an afterlife.

an idea I heard is that ghosts aren't conscious spirits but are more like imprints on the fabric of reality. sort of like an echo. if you shout into a cave, you hear your voice echo back, but it doesn't mean that there is somebody in the cave shouting back at you. in the same way, ghosts could be echoes of events that are being replayed back, but it doesn't mean there is somebody or something conscious actually acting those events out.