Most people are very greedy, man. So i don't see here any reason to be surprised. Top payed sportsmen are often promote some scummy services or even shady casinos, because of money (this is in post USSR countries, where law is doesn't work). And as i see now, in normal countries this happens constantly too. Because of greed.
No matter how hard any government will try to eliminate the corruption in sports, they can simply cannot put it to a complete stop. There are many ways of corruption on the sports like giving your near dear ones opportunities to represent for your country when there are better talent avaible. Also fixed matches are the result of corruption in sports.
And unfortunately, I don't think the situation will change anytime soon. This is already like innate to the system. Since the beginning of human history, corruption was already there, it may be in different form but already a part of our history. What we can do in this situation, is don't be a part of it if you already know that something wrong is going on. If you can't change them, at least don't let yourself eaten by the system.