Atlas wasn't originally a cautious man, but that changed after his reincarnation.
He was in a completely unknown environment with no power whatsoever. He was forced to be cautious.
Plus, there was something deep in his soul that told him not to drop his guard.
He didn't quite understand what it was, but there was no harm in following its will.
Cautiousness allowed him to take risks while being assured of his success. As long as it didn't hinder him, it was a great asset to have.
Especially for a person like him who had a habit of making powerful enemies.
That was why he could look at the twenty Earth Sages before him as obstacles without fear.
He knew how to get through them. He prepared thoroughly before making his entrance, as seen by the several moves he'd made thus far.
His plans were simple, sure, but as someone who didn't really plan before, he was doing a good job learning how to use his intelligence to his own benefit.