Answer:
The likelihood is very high (you said most of the reasons), but not only those... WE CANT CHECK THE WHOLE DANG UNIVERSE! Even if we had enough people for the expeditions- which we don't- we have not figured out how to travel at the speed of light without risking messing up the molecular structure of things... because we aren't light (duh.) I was literally ranting to my dad about this this morning...
