I've worked at Facebook and Google, and I know who can see the messages you send over their platforms. It's scary.

Before we get to passwords, surely you already have in mind that Google knows everything about you. It knows what websites you’ve visited, it knows where you’ve been in the real world thanks to Android and Google Maps, it knows who your friends are thanks to Google Photos. All of that information is readily available if you log in to your Google account. You already have good reason to treat the password for your Google account as if it’s a state secret.