The "same damn reason" is hubris and arrogance (I don't know why you left that out), as he explicitly stated.
"I'm struck by the similarity of the Titanic disaster itself, where the captain was repeatedly warned about ice ahead of his ship, and yet, he steamed up full speed into an ice field on a moonless night, and many people died as a result," Cameron said. "And for a very similar tragedy, where warnings went unheeded (...)"
"Now there's one wreck lying next to the other wreck," he said, "for the same damn reason."
The "same damn reason" is hubris and arrogance (I don't know why you left that out), as he explicitly stated.