Maybe because six aliens are freeloading at the place? One so he can be around his cuties (Toadette and Toadiko) and be a jerk and prankster to everyone else, one to cause mischief, wreck havoc, and try to turn the other five back to the evil side so they can be his majesty's subordinates again, and the other four mainly to keep the first two in check?
Super Mario Boards
Ray Trace
oh come that car wash isn't THAT scary, Bluminescence and Kontrast work at it
...wait Dark Light visits it....okay it's absolutely terrifying now
...wait Dark Light visits it....okay it's absolutely terrifying now
Movie Bowser
Dark Light isn't terrifying
Luigi is because he's sleep deprived and always working
Luigi is because he's sleep deprived and always working
Ray Trace
Well, everyone is scared of Dark Light because she's a cop and she yells a lot.
Sounds absolutely terrifying to me.