Movies were always hit by each other and that was true because no matter what, a movie would only get a gap of 2-3 weeks before another good movie appears on the market.
People were going to talk about that now and the movie that was already running would lose its business. Only in rare cases that a movie would top the North American box office for more than a month.
A lot of times good movies would actually lose a lot because another movie had released around it.
For example, a fantasy action franchise had released its sequel recently but a week after the release, an action comedy movie had been released.
The fantasy movie was praised by critics and everyone who watched it enjoyed it. But the business in the end was only 234 million dollars while the action comedy movie earned double of it.