Mark owns 3 of the most popular apps in existence. Hard to call him a one hit wonder even if his other hits were just recognizing which companies to buy
Not exactly galaxy brain to decide to buy a lottery ticket that's already declared the winning one.
And not like they ruined it, I mean integrated/synergized it.
But also yes it was very much a defensive acquisition, and my point about them not (yet) ruining it shows that there was no plan.
Buying another company from the spoils of your first hit doesn't make you not a one hit wonder. Especially since most of your bidding competitors would have been blocked by antitrust.
I don't know if the same is true for Instagram. I've never used it.
I bet it's really simple from the vantage point of being the owner of the biggest social app with billions to spare.