Because of Michael Jordan's amazing athleticism, skill, and creativity, which inspired many fans and players around the world. He also changed the rules of the game, as the NBA had to adapt to his dominance and innovation.
He was integral in popularizing basketball and the NBA around the world in the 1980s and 1990s, becoming a global cultural icon. His profile on the NBA website states that he "By acclamation, Michael Jordan is the greatest basketball player of all time.