They had him carrying in the suitcases didn't they? Honestly I have a hard time believing those theories about Paddock (and Warner now). It's far from impossible for a lone wolf to plan and carry out a massive attack, FBI themselves admitted that lone wolves are the hardest to stop. Think about terrorist groups regularly getting infiltrated and taken down before carrying out attacks, but for example serial killers and guys like Ted Kaczynski going on for decades without being stopped.