I started the website because it was a great demand for such service in research community. In 2011, I was an active participant in various online communities for scientists (i.e. forums, the technology preceding social networks and still surviving to the present day). What all students and researchers were doing there is helping each other to download literature behind paywalls. I became interested and very involved. Two years before, I already had to pirated many paywalled papers while working on my final university project (which was dedicated to brain-machine interfaces). So I knew well how to do this and had necessary tools. After sending tens or hundreds of research papers manually, I wanted to develop a script that will automate my work. That’s how Sci-Hub started.
via http://arstechnica.com/tech-policy/2016/04/a-spiritual-successor-to-aaron-swartz-is-angering-publishers-all-over-again/