Point 1: Keyword triggers and is actually said are miles apart, as shown by the Alexa creepy laugh episode. There is no practical way of knowing when Alexa has heard a keyword and recorded content around it. Not to mention the Google play incident where a poor wiring job made the devices think the "enable assistant" button was constantly being pressed.
Point 2: My phone, an iPhone, offers a way to turn off the keyword-listening functionality - and presents this switch during initial setup. It also offers a way to turn off all tracking functionality. Apple has no financial gain from lying about this.
Point 3: This comes back to point 1. If you don't know what and when the assistant is listening to, you have no idea what phrases are being collected and shipped off. Also, there are plenty of studies floating about the internet about how "anonymized" search engine queries have been collected, studied, and in many cases paint very personal portraits of the people doing searches.