does imagining +singularity cause depression?
No. Conceivably there are people disposed toward depression at a given time and happen to include thoughts (and bitterness about missing) about a positive singularity in their negative thought spiral at some point. But in those cases I'm unlikely to be impressed with an explanation "imagining +singularity caused their depression". Even then I rather suspect negative singularity thoughts to be a more common toxic thought loop than positive singularity thoughts.
How many people feel despair in imagining a heaven (positive singularity) that they'll miss out on if they don't survive long enough? I don't think about it, but I already have plenty of reasons to like being alive.