They also know the argument between you and your partner, the private secret a friend asked you to share with no one, when you're not going to be home, etc. etc.
I have a cell-phone in my pocket, and I am concerned about the privacy implications. Android is free software, but the driver blobs are not. I do hate that I am compromising for that. Hopefully, there will be more affordable options like the librem phone in the near future.
> If you're worried enough to turn it off sometimes, why not just...not have one in the first place?
The same reason why the fact that I'm worried enough sometimes (e.g., major lightning storms) to unplug various electronics does not mean I choose not to own such electronics in the first place: sometimes isn't all the time, and both the costs of potential vulnerability and the benefit of features (and thus the balance between those two things) can shift with context.
Though, in reality, I'm never actually that worried about my Google Home, I just recognize that this there are adequate existing hardware-based solutions that, should I be concerned at some time—which I can imagine being, though I haven't been—an adequate mitigation exists that doesn't involve not possessing the device.
To me, the difference between the lightning scenario and a digital assistant, is that in the former scenario, I'm protecting the device (and my home) by disconnecting it, but in the latter scenario, I'm protecting myself from the device. It's something inherent to the nature of the device that I'm trying to avoid. I don't feel like those are comparable situations.