They are my beliefs, and I base my beliefs on the shear size of the universe and the material in the universe, consisting of trillions of suns, vast island galaxies of stars with millions of planets orbiting billions of stars systems. I have heard estimates that there are probably a million stars for every single grain of sand on Earth.
No offense but If you had lived hundreds of years ago, I am confident you would have been one of the people that believed the Earth was flat because there was nothing known about the size or shape of the Earth, therefore, it must be flat, or maybe when the sun was eclipsed, you would have thought the sun was being eaten by the sun monster.
I am going to risk the lable of practicing tautology again, by saying, yes, it is possible that no other life exists outside of the microscopic, tiny object we call Earth, but I would seriously doubt it. Try and open your mind a little and dwell on the size of the Galaxy, which is microscopic compared to the Universe. Try to imagine a piece of string with only one end. The Human mind will have difficulty with that image. The vast size of the Universe is beyond Human imagination. Lots can happen outside our little home called Earth.