When the bitcoin develops at 2008, many countries are adopted on it because it was a perfect used for all online transactions. As time goes by many people are using bitcoin nowadays specially on those playing e-gambling, because bitcoin is the most useful currency when playing e-gambling. Bitcoin is not yet spread over the world because there are some people that didn’t now on how to use bitcoin like poor people who doesn’t a deep knowledge about bitcoin because there are some countries doesn’t fully implement bitcoin in their countries.
Bitcoin gambling is huuuge now, and this is the only way I use BTC for now (and that's only because I can increase my BTC amount instead of buying it for fiat). I'd use it only whn the time comes, even if it's several years worth of wait