From what I recall of the LN, Earth actually does understand that he's brought everything upon himself. In terms of his "tantrum," I think it was a matter of a poor translation from novel into manga. In the LN, it was more like being made wanted was the "final straw" that led him to demand the removal of the ring, and the discussion with the dragon lasted longer (which better established why Earth picked a fight). Overall though, it's unwritten both in the manga and the LN, but Earth seems like the kind of guy who claims to not want to stand out, but at the same time strives to prove himself. It's the paradox where you don't want attention, but still want to have achievements (more as a matter of personal pride). The LN TL I read was in first person, so assuming the Japanese version is the same you have to factor in the "unreliable narrator" part of things.