Software engineers are right to be scared of these voice assistants.
The problem is that typical sloppy, glitchy software (and hardware) is poised to record your voice and send it somewhere at any time, and that somewhere will play or record this, because that's what all this stuff more-or-less setup to do. It's already happened! Alexas have already "butt dialed" other people (not just amazon's servers)!
Think a bit broader than that. Things can play out of various speakers in your house and influence these voice assistants. Again, advertisements have already triggered voice assistants. Research has shown how it is possible to play voice assistant commands that humans can't hear. These devices are poised and ready to record anything anytime and send it anywhere, or just use your credentials to do anything.
My laptop is different. It does have a webcam and a microphone, and straight-up locally installed malware could take advantage. But it's not quite the boulder-atop-cliff situation of the voice assistants. I've never enabled Siri, I've disabled it everywhere possible, I don't install junk software, I often check on things in Activity Manager because freakin web apps use so much memory/cpu/network these days, so I would notice. The webcam has a light which is hack-able but it's pretty hard. My phone has Bixby but I've never enabled it, I've never clicked "I agree", I've disabled the button and the swipe activation and the background services which I am able to without rooting the device. It's in reasonable shape.