Because we should not settle for building a world in which every interaction must be assumed adversarial! Obviously risk reduction processes are good because they reduce risk, but we should not accept building entities which are actively trying to defeat us (which is what happens by default).
I don't want such a world either.
So far I'd say these entities are hypothetical (unless you include a lot of other machinery that does unexpected things at times - but then it's a different discussion).
I generally think we are quite good a policing really dangerous things (I think the bioweapon convention is a good example of people agreeing that certain risks are not worth taking).
My (uninformed) take is that presently we have more mundane things to look at when it comes to handling risks in AI and the discussion on much bigger, hypothetical future risks is taking away focus there. Checklist, procedures, saftey mechnics, regulations are kind of "boring" detail work - I get it.