Whatever you think about Facebook, it is not irrelevant to the vast majority of people. What was the pressing issue it was solving? Even the personal computer was not solving a pressing issue at the time. New products create the demand for it and the influence of it only makes sense in retrospect. There are not many solutions that are both achievable and solve obviously huge problems. If there were clear ways to solve these problems, tons of people will have already done it. We solve huge problems by first solving small ones and laddering up.