Hmmm … that’s an interesting question because it has two main points of concern that need to be addressed; the idea that 1) everybody looks at porn; and 2) the porn that people look at is always on the internet.
THE FIRST SECTION
Well, let’s look at the 1st concept first — why … or, rather, whether or not everybody looks at porn to start with.
The answer is both yes and no, the majority of people have some concept of sexual fantasy which they can relate to mentally (in their imagination), but that does not always translate into the use of actual external pornographic material. Humans all have something which ‘turns them on’ and those things, when brought to mind, will have the result of increasing that person’s sexual arousal.
This basically means that we all have some internal perceptions of pornographic content that is part of our mental model of the world in general.
As a side note of interest:
Although it is more common to find that men have full sexual scenes which they play out in their mind like a movie, women more likely relate to an array of kinesthetic physical sensations with only a minimal visual component.
It is, however, possible for both sexes to incorporate a wide variety of sensory awarenesses into their fantasizations. The thing to remember is, no matter who it is, everyone will have one key element that is the main driver behind their sexual arousal in any particular context — it might be visual (something they see) at a bar, auditory (a sound or phrase) they hear in the bedroom, or a specific kinesthetic/physical feeling they get while reading a romance novel.
THE SECOND SECTION
Okay … all of these mental perceptions that get people turned on are simply relating to internal fantasizations that have an end result of sexual arousal — they do not necessarily relate to external pornographic material. Now let’s look at the 2nd idea — the thought with regard to the porn people utilize for sexual fantasies always being on the internet … that belief is less true, and the most likely reason elderly people around the world believe the internet is ALL about sex and porn is because;
- that was the original internet industry that made fist fulls of cash ahead of everything else; and
- with net-porn having been such a profitable industry they were the leaders in web advertising and new internet technologies related to human interactions online.
Overall that is one way of saying that people believe everyone looks at internet porn because all the online advertising about it gives us a sense of social proof — if it says that everyone is doing it then it must be true, right? It’s a basic trick of marketing that creates a socially held belief which may or may not actually be true.
THE CONCLUSION
So, yes it’s true that people have things which turn them on, but that doesn’t prove they look at internet porn (not intentionally anyway … I mean, everybody hates those damn pop-up windows!) — it does not automatically correlate to any facts about the number of people in society that view pornographic material on a regular basis … virtually (on the net) or IRL (in real life).

Now, all this doesn’t mean there is a LOT of internet porn out there … in fact, it’s quite the opposite — there are porno websites dedicated to almost every possible sexual fetish imaginable … and, for anyone wondering how true that could be, just ask any professional web developer to read and explain to you the details of website hosting contracts for online companies.
Internet pornography is the reason anyone starting their own website, blog, forum, or online community has to agree to such detailed restrictions about what one can and cannot post on their web-pages (even Google ads have a strict policy around being shown on sites with even mildly offensive material!).
Here’s another interesting side note:
There is a little-known (and often unspoken about) belief on the world wide web referred to as Rule 34.
Rule 34 is a widely accepted internet ‘rule’ that proclaims pornography or sexually related material exists for any conceivable subject — if something exists, then there is porn of it somewhere on the internet.
… and, just in case you’re still not fully convinced the internet is based around the pornography industry, you can check out Rule 35.