I don't think they are trying to stop their citizens from using the casino; rather, they are just trying to put them in check and also do the taxing, which is where every government doesn't joke with, and from the news that I read, they are asked to comply with the ministry of finance and make a certain amount of deposit if they want to retain or achieve a license to operate legally; the amount appears to be relatively high; I guess it's almost equal to $4.9m dollars.
Everything in brazil is extremely expensive because of taxes. The greatest proof of this is that even with this monstrous collection, the government ends the year with debt and inflation skyrocketing.
Speaking from what you have said so far. Your points are valid. It's wise we still acknowledge the positive impact of gambling on the economy of a country. Brazil is not an exception here. If gambling is one sector where they can generate more funds for taxes and the country's revenue, then the government should be ready to find another means to generate the funds. If no other way, then it will affect the economy in a downturn. Making things worst for the citizens and its worst because gamblers who rely on gambling to survive will be poor.