Both wireless and fiber optics act by transmitting information through electromagnetic waves. The speed of light isn't the interesting constraint here, because

Both wireless and fiber optics act by transmitting information through electromagnetic waves. The speed of light isn't the interesting constraint here, because they're both bound by it. Fiber-optics will have slightly higher latency for the transmission component, because the speed of light is slower in a fiber than through the atmosphere. The real constraint comes in bits per second. With wireless, the ability to improve that comes about by increasing the frequency spectrum in use. You can overlay a signal at, say 1GHz with one at, say, 1.5GHz, and the two signals won't interfere with each other. So the eventual capacity ceiling with wireless transmission is the size of suitable frequency spectrum that is budgeted to it. There is a physical ceiling (can't use 1Khz, for example, or 1PHz) to the amount of spectrum, and therefore, the total wireless bandwidth has a ceiling. With fiber optics, to double bandwidth, you can simply drop a second cable next to the first. So the bandwidth is capped by the number of cables you can lay. This has a much higher ceiling than for wireless.