There is a huge difference between looking for support of the hypothesis that living organisms exist on other exoplanets and believing that
A, intelligent beings evolved in another place,
B, that they are existing now,
C, they have the ability to detect intelligent life hundreds to millions of light years away,
D, that they have the ability to travel vast distances at speeds far faster than light,
E, that they have the technology to transmit data at speeds much faster than the speed of light, AND
F, that they would think like humans.
Considering how quickly life first appeared on earth, it is pretty reasonable to assume that it would happen elsewhere. Whether it would ever evolve to multicellular organisms is yet unknown, though that is also possible.
As for intelligent life which develops high levels of technology? With the number of planets in the universe, it is very possible that it happened more than once. However, I think that the planets on which this happens are few and far between, and that physics put a hard limit on the ability of any such species to detect, contact, or travel to a planet with another technological species.