There are reasons professional athletes can't bet on games they play in, as it ruins games completely, a problem that League of Legends is experiencing right now.
Only recently on his stream, Faker threatened to boycott League of Legends ranked games, due to the appearance of a Chinese player in his game. This wasn't hate based on nationality, however, but on the fact that said player intend Faker's game, to win a bet made on an illegal betting site.
To make matters worse, the player in question is himself, a professional ESports competitor, from the Chinese TES team. Due to the fact that it was Faker who raised all the fuss, and rightfully so, Riot have responded and handed out the punishment to the offender in question.
The root of the problem still remains, though, and that is the illegal betting, with Faker being the largest, but not the only victim of his practice.
As per his own admission, this problem has persisted since 2015, when he got so fed up, that his SOloQ rank was Diamond 1, the minimum to qualify as a professional ESports player.
Removing the root of the problem itself seems unlikely, as Riot are owned by Tencent, who are based in China, and don't seem to have an interest in anything League of Legends related unless it's going to bring in short-term profit, evidenced by the new champion and skin releases being geared toward the Chinese market.
With even professional players participating in this, it's only a matter of time before someone concludes that it's worth it to take a fall during World Championships, and all hell breaks loose.