There is always an advantage to being first; if there wasn't, nobody would ever invest in anything new. Even in your example, the first company to bring gigabit internet to an area can secure some contracts that will still be in place when their competitors respond, so they get a head start when that does happen, which can lead to a longer term market share advantage if they can keep the momentum going. Even if that advantage doesn't last forever, it certainly makes them a lot of money in the meantime.
See: Uber vs Lyft, the iPhone (and, historically, many other Apple products), Coca-Cola, Netflix, etc.
See: Uber vs Lyft, the iPhone (and, historically, many other Apple products), Coca-Cola, Netflix, etc.