Answer:
The best future earnings outcome would come from getting the official degree even if you do not attend any classes.
In the labor market, a degree from the world's best university holds great prestige and increases enormously the possibilities of being hired to high-paying jobs. However, you should make sure that you actually take the courses that you are supposed to have learned while "attending".
The other option is worse because while you would easily be able to demonstrate knowledge and competence, few companies would even consider to hire you if you do not hold a degree.