Ask HN: Who are the most compelling blockchain naysayers?

Blockchain is just a clever data structure, it can't succeed or fail.

Particular implementations of it can fail, financially, or due to bugs.

Energy usage.

For currency: the fact that it is quite difficult for an average person to keep their keys both secure and backed up. For example choosing a secure enough but memorable password for their wallet. Not having their PC hacked while they type in such password etc. As the currencies go up in value so will the sophistication of attacks.

For other applications: Miners fees are high. Any data put into the chain is public and immutable and probably stored forever. So even encrypted messages may be attackable at a future date and the secrets leaked. So you want to stay anonymous there can't be too much interesting data stored in there.

I literally wrote a book attempting this:

https://davidgerard.co.uk/blockchain/

There's a pile of excerpts linked in the sidebar, and the Amazon "look inside!" shows you the first few chapters.

Honestly? Come by Reddit /r/buttcoin. The name gives you a good idea of the seriousness, and it's very much critics, but it's turned out to be the only place on Reddit you can have a serious discussion of blockchainy stuff, 'cos all the others are filled with the frankly delusional.

I bet FT Alphaville has some good ones.