Broad-scale co-evolution means that if you use your co-evolved common sense on the co-evolved natural world, you will broadly speaking be safe. Even with a bit of experimentation on the fringes. Our technological world has then co-evolved with our common sense, which is why despite the several ways our houses have things running through them which can kill us, they don't manage to do it very often.
When you start playing with genetic engineering directly, you're stepping out of your co-evolved "common sense" space into a much more vicious domain, and you get a double-whammy in that not only is this space much more vicious, you are also very very much trying to interact it with intuition built by interactions completely unsuitable for it.
No, people do not understand what they eat, how electricity works, or how their smartphone works, but they are co-evolved with all those things. You are not co-evolved with the results of genetic engineering. You are also not co-evolved with raw exposure to the space of all possible drugs, which is why I left that one out of my list. Notice the incredibly more strict protocols our society uses around those than we use for food, electricity, or smartphones, because we are not co-evolved with arbitrary drug chemicals. None of the other three things are unregulated by any stretch of the imagination, but neither are they regulated to the extent that pharmaceuticals are.
Genetic engineering has a degree of danger beyond anything you are co-evolved with. I'm not directly arguing very much further than "you can't analogize it with anything you are familiar with"; it's a rich question. From a certain point of view (and a pretty good one at that) my entire point is that the question is exponentially more complicated than you are giving it credit for; I'm not trying to actually answer it, implicitly or otherwise. I mean "exponentially" quite carefully and mathematically; part of the co-evolution is that it selects a much, much smaller subset of possibilities out of the full exponential space, resulting in a much smaller "space of interest".