At least in the case of instagram you didnt need hindsight to know it was a good deal. Lots of people thought they price they paid was incredible value on the day it was announced. Plenty of ink has been spilled that year about facebook potentially being in trouble with mobile and instagram seemed at the time to be an obvious solution to the problem.
That is not my recollection whatsoever. A quick read through the HN reactions that day (https://news.ycombinator.com/item?id=3817840) shows a mix of bewilderment and belief that this is a defensive play. Very few people actually opined that Instagram represented much actual value.
Yeah, I admit completely that I thought they were massively overpaying for Instagram at the time. I also shared the highest OP's sentiment that I didn't think FB was a good investment for the same reason (that people would migrate from FB to the next thing as fast as folks moved off of MySpace).
I was absolutely and utterly wrong on both accounts. Part of it was definitely wishful thinking, though, as I dislike FB by one or two orders of magnitude more than any other software company.
But yes, I'd say their acquisitions were not completely obvious slam dunks.
They also tried to be Snap, ofc, but my recollection is that Snap refused. Interestingly, folks have probably flip-flopped over the last few years in wondering whether that would've been good or bad for FB.
