Brazilian Jiu-Jitsu (BJJ) is widely regarded as one of the fastest-growing sports in the world for several reasons:

Effectiveness in Mixed Martial Arts (MMA): BJJ is a core discipline in MMA, especially due to its emphasis on ground fighting and submission holds. The rise of the UFC and other MMA organizations has helped popularize BJJ, as many top fighters use BJJ techniques.
Accessible to All Ages and Body Types: BJJ's appeal lies in the fact that it doesn’t rely solely on strength or size. Instead, it focuses on leverage, technique, and strategy, making it suitable for a wide range of participants, including kids, women, and older adults.
Practical Self-Defense: BJJ has proven itself as an effective self-defense system in real-life scenarios, which adds to its attractiveness. Many people are drawn to it for its practicality in defending oneself in close-quarters situations.
Global Growth: BJJ has expanded from its roots in Brazil and the Gracie family to gyms all over the world. From the U.S. to Europe, Asia, and beyond, BJJ tournaments and schools have seen a massive increase in participation.
Mental and Physical Challenge: Unlike some sports that rely heavily on athleticism, BJJ involves a combination of mental strategy (akin to chess) and physical skill. This dual challenge draws in people who appreciate both aspects.
Community and Culture: The BJJ community is known for its camaraderie and culture of respect and discipline. Many practitioners form strong bonds within their gyms, which encourages long-term participation.

This blend of factors has made BJJ one of the fastest-growing sports, with an ever-expanding number of tournaments, gyms, and global participants.