Bitcoin is more popular on using in gambling sites or online, the advantages was totally use by its users the anonimity on betting to the games.
when in bitcoin it is pretty transparent , you can see your money come ,
that whats make bitcoin more than fit into online casino ,
i expect in few years ahead most online casino will accept bitcoin as payment.
means their privacy about their identity will secure with bitcoin ,
no documents asked , nothing , just an email + password and you are good to go ,
that is enough to attract more player , but most casino still doubt to accept bitcoin due some reasons.