I read through the entire affidavit when it originally came out as I have an interest in online gambling... but I couldn't figure out what exactly the FBI was a

I read through the entire affidavit when it originally came out as I have an interest in online gambling... but I couldn't figure out what exactly the FBI was after these asian gamblers for... the only thing it said was that they had multiple tvs and internet connections going into one suite and when the FBI saw what they were doing, it looked like they were only betting on World Cup matches over the internet. There has to be more to it... I know online gambling is illegal in the USA, but why get the FBI involved because some foreigners are betting big online?