Is the internet only connected by optical cable? Why can't we use satellites? Isn't wireless network and wired network integrated?

There are many disadvantages in using satellites, because radio signals are easily interfered, which leads to the decline of network quality. However, the switching ability of satellites is limited, the cost is relatively high, the service life of equipment is short, the maintainability is poor, and the data security is poor (easy to be intercepted), so the advantages of optical cables are outstanding. Optical cable is not easily influenced by the outside world (such as earthquake and man-made damage), with stable signal, high transmission efficiency, low cost and good maintainability.