Most of the previous answers have pretty much addressed why it's not safe effectively. Personally, no matter how armed you are, I don't think anyone is ever truly "safe" from dangerous people. Especially if you're a person with a conscience who's never fired a gun before. Without the mental training and discipline it takes to fatally wound another human being, even if it's in self-defence, it's a big challenge, and that immediately puts you at a disadvantage compared to them.