Legitimate, no snark, question: what is an “Ethereum Researcher”?

Writer. Building @pinatacloud. Tinkering with a Farcaster native alternative to GoodReads: https://readcast.xyz \ https://polluterofminds.com

simply research on the core Ethereum protocol or something closely adjacent.
- consensus protocols
- data availability sampling
- p2p protocol design
- cryptoeconomics
- Eth-relevant applied cryptography
- smart contract analysis & language design
- L2

Real World Ethereum 🌎 
building /daimo ✳️ 

And is that for a company usually? For fun? For the Ethereum Foundation? I think that's probably where I'm most confused. Is it a job or a fun thing people do?

the EF is probably the main employer of ethereum researchers, but there are also other orgs (Consensys, various L2s, etc), academics like Yan Zhang, and independent (often anon) researchers like Hasu and polynya. Hasu works for Flashbots, polynya is unknown afaik

It varies. The foundation employs research teams now, but there are also cos focused on ETH that have employed people to do technical research that covers improvements to the ETH core protocol.