Don’t be paranoid. An Eco Dot literally can’t tell you the time w/o phoning home. You can watch the network traffic it produces. No way it’s transmitting 24h of audio. And if you think about it, millions of Alexa devices recording 24/7 audio would generate more traffic than porn. And that’s before Amazon has paid a nickel to process any of that audio.
When it comes to eavesdropping on “every little conversation” They don’t, they can’t, it would be stupid to try.