They (basically any large online retailer or advertiser) are, in fact, listening to everything you say near your phone, near your alexa, your echo, your smart device.
Linking heard words and phrases with your known shopping activity + a gigantic dataset + statistical analysis = they can predict all kinds of things about you, with shockingly high accuracy, and thus aim products at you.
You know how archaeologists and detectives can make a decent profile of a person or group’s daily lifestyle by analyzing your garbage?
Welcome to the cyberpunk dystopia version of that.