Maybe, but if a state actor has achieved this ability, I doubt they would make its existence public knowledge by stealing a few billion US$ in btc. That's chump

Maybe, but if a state actor has achieved this ability, I doubt they would make its existence public knowledge by stealing a few billion US$ in btc. That's chump change compared to the value of being able to surreptitiously crack the cryptographically secure messages of everybody in the world. Note I'm not saying that I actually think someone has achieved this, I just don't think "no one is stealing btc" is a good non-existence test.