@Vincenzo -- A good compromise is a router that receives a fiber optic, high speed signal but connects with other computers through WiFi connections. While the speed of WiFi isn't quite up to that of pure fiber optics, it is usually more than fast enough.
But there's something to keep in mind. Those WiFi connections seem to get "confused" from time to time and boot computers off the network. That means the routers have to be reset every now and again.
The most reliable connection is through traditional wires hooking up to a router. For now, that is the setup that makes the most sense for a lot of businesses.