why do some online casinos have tournament brackets that are totally rigged

I've noticed some of these casino tourneys always end up with the same small crowd at the top or some random accounts that don't seem active otherwise. It's wild how out of nowhere these players rack up insane scores right before the thing ends. Makes me wonder how transparent the brackets really are or if it's just RNG manipulated in ways we can't check.

I get that the house always wins, but you'd think there would at least be some kind of public list or proof of fair play with these brackets. Instead, it just feels like the whole thing is just a sales trick to get people to play harder. Curious what everyone else sees with this.