This should change soon, according to Riot Games. The studio published a letter yesterday in which it promised that it would take steps to improve the situation for pro teams, including expanded revenue sharing and a more stable gaming scene.
“We’ll share LoL esports revenue streams and collaborate with our partners to develop new business models and actively shape the league,” Riot said. “We want these partners to have permanent stakes, to be invested in a stable future, and to profit from the continued success of the sport […] We need to unlock new revenue streams. We need to grow the pie so that there’s more for teams and pros.”
Source: Riot Games via SB Nation