According to NASA's research, there are 300 million Earth-like planets within this single galaxy which could potentially harbor life. Statistically speaking, it's impossible for us to be alone in outer space.
As to why we haven't found anyone yet, we've only been searching for a few decades; not even the closest Earth-like planet could receive a radio transmission in such a short time. Assuming they had technology capable of receiving a transmission, and assuming they were able to decipher our language into something translatable, these hypothetical lifeforms might choose to ignore it.
"If you’re a hunter in a dark jungle filled with other hunters, the last thing you want to do is shout, ‘Here I am!’"
This is a paraphrasing of the Fermi Paradox. Broadcasting a signal into outer space could potentially lead to contact with an as-of-yet unknown ally...but it could also bring other, more predatory species down on our heads.
Personally? I'd rather err on the side of caution and tell those scientists: "Hey! Pipe down, will you?!"