BBC [bbc.co.uk]:
Credible-seeming statistics suggest that about one in seven web searches is for porn [bbc.co.uk]. This is not trivial - but of course it means that six in seven web searches are not.
The most-visited porn website - Pornhub - is roughly as popular as the likes of Netflix and LinkedIn. That's pretty popular but still only enough to rank 28th in the world when I checked.
...
New technologies often tend to be expensive and unreliable. They need to find a niche market of early adopters, whose custom helps the technology to develop.Once it is cheaper and more reliable, it finds a bigger market, and a much broader range of uses.
There is a theory that pornography played this role in the development of the internet, and a whole range of other technologies. Does it stack up?
Perhaps in 10 years' time we'll be asking what role robots were created for; will the answer be "porn?"