It's actually sufficient that he simply hasn't revealed the prize in the other 98 picks. Of course, it would make for poor drama if he just happened to open the

It's actually sufficient that he simply hasn't revealed the prize in the other 98 picks. Of course, it would make for poor drama if he just happened to open the prize in the process, but you can imagine a construction where he's picking 98/99 of the other boxes out of lotto machine and offers you the chance to switch if, at the end of the process, none of the doors he opened contained the prize. It'll just be a pretty silly show the 98% of the time that the host just opens the prize in the middle of the drawing.