> Most log messages are useless 99.99% of the time. Best likely outcome is that its turned into a metric. The once in the blue moon outcome is that it tells you what went wrong when something crashed.

If it crashes, it's probably some scenario that was not properly handled. If it's not properly handled, it's also likely not properly logged. That's why you need verbose logs -- once in a blue moon you need to have the ability to retrospectively investigate something in the past that was not thought through, without using a time machine.

This is more common in the financial world where audit trail is required to be kept long term for regulation. Some auditor may ask you for proof that you have done a unit test for a function 3 years ago.

Every organization needs to find their balance between storage cost and quality of observability. I prefer to keep as much data as we are financially allowed. If Binance is happy to pay to store 100PB logs, good for them!

"Do we absolutely need this data or not" is a very tough question. Instead, I usually ask "how long do we need to keep this data" and apply proper retention policy. That's a much easier question to answer for everyone.