If you live in a city right now there are millions of networked computers that humans depend on in their everyday life and do not want to turn off. Many of those computers keep humans alive (grid control, traffic control, comms, hospitals etc). Some are actual robotic killing machines but most have other purposes. Hardly any are air-gapped nowadays and all our security assumes the network nodes have no agency.
A super intelligence residing in that network would be very difficult to kill and could very easily kill lots of people (destroy a dam for example), however that sort of crude threat is unlikely to be a problem. There are lots of potentially bad scenarios though many of them involving the wrong sort of dictator getting control of such an intelligence. There are legitimate concerns here IMO.