The problem is, the fight wasn't even finalized until a few weeks ago. Yes, there were rumbling rumors for months, but nothing was for sure, and most people don't automatically backtrack their numbers for something nobody really knows for sure how much effect it would have.
The high predicts were also based on hopefully insanely good WOM, like the first one had.
Without the fight (plus Kentucky Derby, plus Spurs/Clips Game 7), plus better WOM, it's not a crazy prediction to believe it would break the record at all.