https://www.cnet.com/roadshow/news/tesla-referral-program-ending-february/

The referral program has been a cause of much internet bickering between journalists on what constitutes an ethical violation and even jokes on shows such as Silicon Valley. It probably helped to sell a lot of cars, but its popularity and subsequent costs were ultimately the program's undoing, according to further tweets from Musk.

"The program was great in the beginning to spread the word about Tesla and to get one in everyone's hands, as time went on the system was losing more and more money as more owners were getting referral codes and the Model 3 production ramped up," said Rich Benoit of YouTube's popular Rich Rebuilds, in a statement to Roadshow. "People like myself that are currently enjoying the perks may not like it, but Tesla can't give expensive things away forever. That and I'm getting close to getting a free roadster and Elon wanted to put a stop to that!"