It is their fault. It is 100% their fault that a downvote turned them into a toxic human being who wants to cause harm through any means possible, and saying otherwise makes you part of the problem.
I 100% disagree
Making this statement is like saying there is no such thing as emotions taking over rational behavior in human nature. The reality is that downvotes trigger people like crazy especially when they serve injustice and only a minority of people have are actually capable to overwrite their emotional drives. It's not their fault, it's how the brain works.