It's hard to make proper judgement if there is limited information shared by the accused.
Maybe what the sportsbook representatives can do is to try to use independent arbitrators of their choice to solve such disputes if they can not share sensitive information with the community.
Having words exchanged with different casino owners and casino representative, I realized for them this community is just another advertising platform like many other platforms. The community and the bitcoin is attached closely to our daily life but for them bitcoin community is an experiment, if advertising works then they continue but when they find difficulties they focus on other platforms where they get easy return of investment.
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There are many things about sportsbook and casino that I do not think fair but at the same time they are business institute, they run by their terms. When big companies find a user is trying to take advantages from them, they starts limiting the users. For that reason it's impossible to continue such betting [taking advantage, group betting, arbitrage betting] with big sportsbook but with small sportsbook I think a professional gambler can take the opportunity easily.