It is due to the principle: "The entropy (disorder) of the universe increases with time". This means, events that increase the entropy are supported, and the other events need effort... Hence destruction, that tries to increase the disorder can be achieved in a smoother way when compared to the construction... So what if we can reverse this property of entropy?? Yeah, that is what you observed in the Tenet... Hope you understood the post... Do you also know such cool things? Don't forget to share in the comments section, and help us reach the 'Eternal Thing'... P.S. You can also express your ideas about this point of view through the comments..