Tesla and SpaceX founder Elon Musk displayed his entrepreneurial spirit in college when he transformed his house into a nightclub to pay his rent.

After Musk transferred from Queen’s University to the University of Pennsylvania, he rented a large house, threw huge parties attracting upwards of 1,000 people and charged students for admission.

His roommate, entrepreneur and investor Adeo Ressi, helped coordinate the household nightclub during Musk’s years at Penn. In an interview with Vogue, however, Ressi said that Musk was disinterested in the parties and saw them as strictly business. Ressi said:

“There were some nights where I’d be like, ‘Where’s Elon?’ and I’d go up to his room and pound on the door and he’s in there alone playing a video game.”

While it may seem strange to play video games while other students are having the time of their lives downstairs, Musk is known for his sometimes eccentric behavior.

In high school, Musk was often bullied and treated as an outcast. At one point the bullying got so bad that Musk was hospitalized. Musk told Vogue:

“South Africa was quite a violent place. There was a level of violence growing up that wouldn’t be tolerated in any American school. It was like Lord of the Flies. There were a couple of gangs that were pretty evil, and they picked their victims and I was one of them. I think part of what set them off was that I ended up sticking up for this one kid who they were relentless on. And that made me a target.”