Game theory-wise, though, a ransomware operator knows that a victim won't pay in the first place if they have credible reason to believe the ransomer won't stay true to their word.
My understanding is that most of them genuinely want to maintain a reputation of honesty (like old-school pirates who would hold ships/items/people for ransom), despite the obvious immorality of what they're doing. In some cases this is partly due to a code of ethics/honor (like old pirate codes), but in general it's because their goal is profit, and total profit can be impacted if many victims don't believe there's any point to paying the ransom.
You can see an interesting interview with a ransomware operator here: https://news.ycombinator.com/item?id=27097061