When you think about it, I imagine it's a negative feedback loop. Guy dies, turns into an evil spirit, goes onto kill more guys with a chsnce some of them turn into evil spirits as well.
What's expected to happen, then? Leaving the money to deteriorate on its own? Pick it up and disposed of it in a trashcan? Left with the local police box?
"I've never seen this gag in a manga before." -Statement I uttered three times for this chapter alone.
Incredible stuff, looking forward to next month for more.