Just think of the technology needed. I don't think we will ever have the technology to be able to visit other planets revolving around even the closest stars. I think mankind will destroy itself before then. I believe this is probably the curse of intelligence; it will allow us to create technology we are not evolved enough to use responsibly. We have already done so, I believe, as I believe mankind is creating global warming. I believe this is the fate of all intelligent beings (not necessarily global warming, but self-destruction). I cannot support this possition, as it is untestable speculation, so don't ask me to.
My question then is:
So what makes anyone think aliens can visit us?