The question needs to be further defined, as usefulness can be evaluated in broad ways. To refactor the question: 1) Intrinsic usefulness, for personal improve

The question needs to be further defined, as usefulness can be evaluated in broad ways. To refactor the question: 1) Intrinsic usefulness, for personal improvement, satisfaction, development or solving one's own itch. Online self education is transformative. There was a time when specialized knowledge and technical knowledge was difficult to obtain. Unless you lived in a large city or a university town, your book choices were limited. There was no Amazon, no stack overflow, no abundance of technical content. For intrinsic benefit, online self-education is unequivocally yes. As far as whether online self education is useful for participation in the employment market is less clear. At this time, it is not clear whether online self education has the signaling value to the market. This is less clear. If there is some form of certification that can be universally agreed upon then it will have more value. However at this time, this doesn't exist.