It was because of the destruction of the Republic and its morality that the Empire rose. But it contained the same destructive forces which had destroyed the Republic.
These forces became an uncontrollable violence against people and places once moral control was gone. Cato had fought for a retention of Republican virtue by attacking the love of luxury and dissipation. But it was irresistible without a moral core undermined by emerging rationalism and philosophy.
An empire based upon brute force cannot last.
Nothing can last. Empires rise, and empires fall. Human planning and random events will topple even the mightiest in time.