The biggest forex related website is
Forex Factory, with all the news data, and pretty much everyone who is trading is there on the forums. 800k registered members and many anonymous, so definitely over a million regular users.
But as said above, forex is just another business, it might seem easy to get in, but its not different from running any other business. I would even say its much more difficult, because it takes a high IQ, good understanding of numbers, statistics, economic fundamentals and human psychology. And then it takes hours every day looking at the charts. So it can't be done as a side job and thats why most people lose money. There are probably 1% of traders who not only make money regularly, but also make enough to live just off it.