Because if they exists they got here... and we didn't get there...
However, we got to the Moon, and landed the Curiosity Rover on Mars; Leonardo Da Vinci, Galileo, and Isaac Newton did not. By that logic, the thinking must be that makes us of superior intelligence to Leonardo De Vinci, Galileo, and Isaac Newton. Right?
My answer is that they probably are not. . . except the empirical evidence that they succeeded in not blowing themselves into Kingdom come by way of nuclear wars, internecine religious wars, cut-throat business wars, philosophical economic wars, and somehow found a way to survive their technological capability to destroy themselves, and survive the ennui of not having to work for their daily bread in a world in which everything can be made for them by their technology. . .
But that seeing as how we think that many of the stars we see are far older than is our own star, any planets that may be orbiting those stars might have started developing life earlier than ours. . . and that life may have had a big head start on developing intelligent life and therefore technology way before us. Some of them may have had millions of years of technological and sociological history that has taught them how to use technology and also how to survive it.
On the other hand, they may have reached the point where their technology is so far beyond them, they don't understand it at all anymore and merely use it. To them Arthur C. Clarke's third law has become an unconscious LAW. . . that any technology sufficiently advanced is indistinguishable from magic.
For them, all they would need to say is I want. . . and their Deus ex Machina (the god of the machine) would make it happen. . . without their ever needing to understand how it was accomplished, having long forgotten the why and how.