2017-2022 I would've said the Ethereum foundation and various DeFi startups. If you look at what Ethereum accomplished with proof of stake, it's quite remarkable. The game theory alone for proof of stake is thorny as hell, and then they built a working secure implementation and upgraded a distributed network of unaffiliated organizations who all voluntarily run nodes, all without major hitches or anyone's funds being lost. That's huge, and more impressive than anything Google's done in the last 5 years.

Since 2022, I would probably say the various LLM owners: OpenAI, Anthropic, Character.AI, etc. The complexity here isn't in the basic transformer architecture though (which was invented by Google in 2017), but in the data infrastructure that hoovered up all the data on the web to train it on, as well as the fine-tuning on various use-cases.

Not surprisingly, good engineers follow the money: these have also been the lucrative industries in those time periods.