Why Forex trading is, like poker, a zero-sum game ?

Forex is a risky investment and it is not suitable for all investors.. so it takes a practice and patience to be successful at it. As famous investor Warren Buffet once said : "Risk comes from not knowing what you're doing."
Forex trading is, like poker, a zero-sum game. Many people lose in the long term, just like in poker, because of their skills.
But in my opinion, the most important thing about trading is that you're right at least 50 % of the time. Just do the math.