If you took a drink every time an economist used "network effects" to explain why Big Tech is so big, you'd get very, very drunk.
To be fair to economists, network effects *are* important to the Big Tech story.
A system is said to have network effects if it gets better when more people use it. That certainly describes Facebook - you join FB because of the friends that are already there, and then someone else joins because you're there.
https://en.wikipedia.org/wiki/Network_effect
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