Well this is a good chance to learn. The people in charge of businesses and business strategy spend billions on advertising, so there's probably a good reason to do so. With almost everything, you're either climbing or you're falling. Everything is a race. It doesn't matter if you're in first, you have to keep running. And actually being in first is a great time to push extra hard, because then you increase the gap between you and the next guy, meaning everybody will focus more on each other and less on you. 

Have you played Mario Kart? It's basically the same thing. If you play online, many times the player in 1st place is almost half a lap ahead of everybody else, while everybody else keeps gaining and losing places. When you're that far ahead, nobody else can ever touch you except maybe with a blue shell or lightning, and even if they hit you, you're so far ahead that nobody will catch up anyway. 

The other players can't just focus on 1st place, they also have to pay attention to the players behind them to make sure they don't catch up (dropping bananas or throwing shells backwards) as well as the players more closely in front to try and pass them (throwing red shells or fireballs). They have to focus on beating 10 other players, and 10 other players are focused on beating them. 

1st place just has to maintain its lead and it's usually untouchable. McDonald's is in first place compared to local Mom and Pop places, or even smaller chains. McDonald's isn't competing, it's just making sure that it keeps the gap large, and grows it if possible