Oh and you did not respond to the point I mentioned about you being wrong about ethernet (category 5 cable) being used in every type of internet connection that uses a router. all a Ethernet cable does is bridge router to pc it does not bring the connection to your home
Since you don't want to just accept it was a joke and move on and seem intent on dwelling on this crap:
YOU'RE WRONG!
You can get fibre optic routers and fibre optic network cards. You can also get (or at least could) get modems for a PC.
As such you can easily get the internet without any cat 5 cables.
Also, ethernet does not refer to the cable. It refers primarily to the data structure.
You can have ethernet over optic fibre, ethernet over coaxial cable, ethernet over twisted pair (e.g. cat 5 or cat 6 cables, typically with 8P8C connectors, which are not RJ45, that is a different standard), and depending upon how you have it set up, you can even have wireless ethernet.
Ethernet defines the data link layer, that is how the data is structured with various bits and bytes. It does not define the physical layer, as such any physical layer can be used.
Similarly, you can also use cat 5 cables for a variety of interfaces, not just ethernet. For example, some serial communications, like RS485 will use cat 5 cables. ADSL can also be carried over cat-5 cables, without being ethernet.
Regardless, that still doesn't address what he actually said.
He didn't say the internet comes to the computer without using ethernet cables.
Instead he said the fibre optic internet is slower than ethernet.
For most users, this will be the case.
They have fibre optic internet which goes to their router. This is typically a relatively slow connection varying from 10s to 100s (and occasionally up to 1000) Mb/s.
Conversely, ethernet routers are typically 1000 Mb/s, and if not, they will almost certainly be 100 Mb/s or faster.
As such, the typical home internet setup has a fast internal ethernet with a much slower internet.