I would agree with # 4 that absolutely perfect safety is impossible (since almost anything can happen). One might call therefore call safety an "illusion," but that seems too strong a claim. If I am standing in the middle of my yard, it is entirely possible that I will be hit by a meteor, but that isn't likely to happen. My sense of safety, then, is not an "illusion" (that is, it is not nonsensical to feel reasonably safe), even if perfect safety can never be guaranteed.
Perfect safety is not an illusion, but it is an impossibility. Reasonable safety, though, is not; it is perfectly reasonable to take steps to raise the probability that you will not burn your own house down, or fall on an upturned rake, or be sliced in half by an industrial machine. We take steps to increase reasonable safety, but we cannot guarantee it to anyone. Therefore, you might say that perfect safety is unreasonable, but acceptable safety is reasonable within limits of common sense and risk.
Certainly safety is an illusion. We are never safe anywhere at any time. We know that bad things happen all the time but we just figure they won't happen to us. As I type right now, something in my house's wiring could go wrong and the house could burn down. I could have a heart attack in the next couple minutes. We're never completely safe.