No, it is not true that Forex trading is the source of business for all online businesses. While Forex trading is a popular and lucrative form of online business, there are many other types of online businesses that generate revenue through e-commerce, advertising, affiliate marketing, and other models. Each business has its unique strengths and challenges, and the key to success is finding the right opportunity that matches your skills, interests, and resources. Forex trading can be a profitable business for those who have the necessary knowledge, skills, and risk tolerance, but it's not the only option for online entrepreneurs.