Gods wither away when their believers don't follow them anymore. They depend on you, which is often times a sign of a faulty relationship. It's explained here: Terry Pratchett - Small Gods. ;)
Recently I watched a talk where Slavoj Zizek brought up a question that was apparently very popular in the Middle Ages in Europe:
Do the people in Heaven get to watch the people in Hell suffer ... like some kind of Heaven version Netflix playing the show Tiger King ?
Because it seems that lots of Xians who see themselves as saved think the answer is "no" so that they must make and watch sinners suffer here on earth before joining Abraham's bosom.