And other factors like total number of movies available and overall weekend attendance compared to other weekends in 2018. It appears this weekend did not have a high turnout overall. Only four other weekends had lower revenue than this weekend according to BOM. I suppose folks are getting some last summer outdoor activities in before the cold hits.
If The Predator had been released in June - high revenue weekends of the big releases - it may not have even broke into the top 10-15 for its debut.
Also, The Predator's competition for this weekend....... It's strongest competitor was The Nun, not exactly a box office heavyweight. Nor did its widest opening release hamper it's performance, at 4,037 theaters, which is about average. Black Panther widest opening release was fewer than that.
So yea, at the moment it's number one, but it has an ugly asterisk next to it.