Well first off they use private accounts so it's not announcing to the world, just people that they know. And many of them post the bad stuff too, especially when they are soliciting advice.
I got it. I never thought of people using Instagram or any other social media for soliciting advice on sensitive personal topics which ought to be ephemeral and private (encrypted instead of available to thousands of employees at Facebook and elsewhere).
I have a hard time believing every friend of yours is a security engineer. And if they are, maybe you need to pop out of that friend bubble a bit and see how the other 99.9999% interact with social media.