The quote starts out with “Everything,” not “Most of” or “In general, much of.” It starts out with a categorical, an absolute. So is this statement itself inherently self-contradictory or not? Is this statement, attributed to Marcus Aurelius, merely his opinion or is it a fact? Is it his perspective or is it truth?
Shouldn’t these purported words of Marcus Aurelius be rendered, “Everything we hear, including this, is an opinion, not a fact”? That would then be closer to an internally consistent and therefore truthful or factual statement, would it not?
But it also might be that what Aurelius really wants to say is that “It’s a fact that everything we hear is an opinion, not a fact, except for this, this–what I am saying right here and now–is actually a fact and not an opinion, and thus is excluded from being merely an opinion.”
See? That’s the game of subjectivity.