Average 3 bitcoin per minute is crazy, these gamblers surely got a lot of minute and they are making gambling as their source of income. These people surely loves the way on how they can gamble with bitcoin. Since it was mentioned that bitcoin is more secured rather than going to casino and gamble out what you've got.
There are websites like this set up to check statistics.
https://thebitcoinstrip.com/stats/2017-02-01-to-2017-02-28