It's very reminiscent of that feeling when you were a child that adults have everything figured out, and so you're in a big hurry to get there because then everything will make sense.
Then that moment of dawning horror when you see that nobody knows what the fuck they're doing and everyone is faking it at best, and just a child playing dress-up at worst.
Google has certainly figured out a number of things, but anyone using 2.5 million servers in 2016 on a planet of only 7 billion people is playing dress-up.
I’d assume 2.5M refers to the number of containers, not physical machines. And that since containers are virtualised and largely a developer convenience, there’s not a big reason to try keeping that number low.
Speaking as someone less than one order of magnitude below that, it takes us about ~100-200 cores. (Depending on how you amortize shared infrastructure like our Kafka brokers, etc.) So even 10x'ing our infrastructure I can't imagine 50k servers.