There's a divide though in "alien believers".

I absolutely believe that other life exists in our vast universe. This is a pretty common opinion among scientific thinkers, space enthusiasts etc. that the universe is simply too huge for us to be all alone.

I also believe that due to that vastness, we'll never meet any aliens, unless we punch into Europa someday and there happen to be some fish down there.

UFO enthusiasts, on the other hand, have a position that is much less supported by science.