That's what they all say.
Humans are social creatures and the main motivator for anyone to do anything in public is to "show off" or "be interesting". "All is vanity".
That isn't necessarily a bad thing. Without a desire to compete, impress, prove our worth and so on we'd be living in huts. But it's something to be aware of and something that should be tempered.
I think the pendulum is swinging away from modesty plus self-reflection and towards "people documenting their lives in public".