Jesus, Mary and Joseph. There's so much wrong in this comment I almost went blind.
First: where did you even get the idea that Satan only killed 6 people? I'll also ask you why he was permitted. There was, of course, a reason behind that. But still. Why would God give Satan such an order? I don't remember him being on speaking terms with Satan. Ever. The only time Satan remotely spoke to God (holy spirit) was when he tempted him in the mountains and all.
Secondly: God didn't anticipate that Satan would fall out of grace. He could have seen it. Omniscient and all. Considered that. But as I have vividly pointed out, God in vivid depiction is told as a non-living being that has enough respect and honor to give freedom to those whom want it. Actually it is so freely given, you could do practically anything you want without him being in your business. Except when it really calls for it. Unless you are affecting what he so wants to protect, all in the name of goodness and virtue. I probably should have left this at "business" since the last parts will fuel even more argument on your side. And yes, suffering is a pretty awful thing and no one wants to have it, but it is an explained punishment in the Bible for "your" kind. Our kind. Who disrespected a simple order. I think it's them who've destroyed us more than he might have. The capacity to sin part is an erroneousness that needs to be corrected. God initially didn't give that to anyone. Adam and Eve were oblivious as little children. Sin only manifested in their consciousness when Satan himself appeared as the snake in the tree. So God didn't give them anything. It was all Satan's influence. In which case, they wouldn't have had intelligence.
Thirdly: the fault is most likely ours. Our ancestors are the ones who ate from the tree about which they were told and instructed not to eat from. Although it was also irrational to toss us into the same fire as them, we do quintessentially come from them and are a product of what they did. Hence the susceptibility to the punishments effected.