You all thinking as if to trade successfully is as easy as starting up your pc at home or at the office. You all forget the time and energy you would have to spend in learning, time which they have but not the energy. One or two retirees maybe, but certainly most of them don't. Most people retired at the age of 55 to 60. Let's consider you had an early start of 50 instead. Can you guarantee you can make it by 5 years? Nobody can guarantee anything. What if you make it when you're 70 (And you die at 71)?
I'd say your chances to start learning about forex trading and succeed by the time you retired is about the same as learning to drive Formula 1 and hope to win the world championship before you die. The highest probability is you died on the track for your heart couldn't stand it.