I would say that it is a combination of things. The human desire to communicate with others, the desire to investigate new things and the falling costs of computers, smart phones and internet access.
People love to communicate and learn about others, where they live, what they do, opinions on the weather. We buy, sell and communicate. Businesses have made it easy for us to buy things from our computers and phones. Places such as public libraries are crammed with computers for public use. Where the computer was a machine for specialists and electronics hobbyists thirty years ago, they are now so inexpensive they are disposable. Almost everyone today has access to computers more powerful than we hobbyists in the 1980's dreamed, the first computer I built in 1981, had 1K of memory and no keyboard, just a plastic contact sheet printed with letters and program instructions and a series of black blobs was the sophistication of the graphics. That computer then cost me the equivalent of $500 and took me three weeks to construct.
Today I pay $500 and I get a machine with gigabytes of memory, graphics which are no longer blobs and a keyboard, just pull it from the box and attach a screen and go.
I think we are still in the infancy of human-computer interraction. The use of computers will continue to spread, though we are getting near to saturation point for the total number of users as the number gets to the total population of the Earth increases will slow. But then also comes the problems of keeping all those people connected. So far it seems to have been easy, in the future it may be less so that is when people will seek an alternative to the internet. That alternative may be sitting in a lab somewhere, waiting it's turn to blossom.