They know that Paddock also rented a room overlooking Lollapalooza in Chicago. There's evidence that he was considering other locations, not just casinos. Doesn't make sense that this was just a vendetta because a casino didn't comp him a penthouse.

This seems like a very weak motive theory to cover the fact that authorities haven't people able to come up with any answers in 6 years. So much about this case is so weird.