> Almost by definition, its impossible for more than one party to control 51% of all hashing power. I suppose they meant, that many parties do have that much p

> Almost by definition, its impossible for more than one party to control 51% of all hashing power. I suppose they meant, that many parties do have that much potential compute but they use it for other things. But they could in theory switch to computing bitcoin hashes and control 51%, and in turn some other party can do the same etc... Obviously you're right that eventually one party can own 51%, but that doesn't mean only one party can successfully perform 51% attack, since % of hashing power can change by time.