First, fiber rules out PoE, which is one of the major advantages to a wired network to begin with. Devices like APs, cameras, and phones will need local power, which is going to add a lot of expense and/or installation complexity. In most installations today power delivery is one of the main purposes of network cabling.

You'll also need either fiber interfaces or media converters, which besides cost is an installation complexity. It'll add another thing you need power for and more equipment to conceal (or leave visible...) at each AP. Even assuming all of your devices are all full-on desktop computers I think the higher price of fiber NICs will eat much of your savings.