You send them the payment, they tell you they deleted the data, but they also sell the data to 10 other customers over the dark-web.
Why would you ever trust people who are inherently trustworthy and who are trying to screw you? While also encouraging further ransomware crimes in the future.
If you don’t pay, the odds they will publish your data are closer to 100%. If you do pay, the odds have historically been much closer to 0% than 100%
You aren’t paying to be sure, but to improve your chances.