Your last 4 words are 100% INCORRECT!!
There is plenty of VERY Credible evidence. Have you ever read a book on the subject? I'm not talking about some abduction case, or some other fringe article. I'm talking about a book that goes back to the beginning and steps you through the subject from day 1 up to today? I think you might be very surprised by what you learn. And trust me, you have much to learn on this subject.
Here's a couple for you to ponder:
Above Top Secret, by Timothy Good.
Blank Check, (Author ??) - Attempts to follow the money with regards to Black Projects.
Alien Agenda, by Jim Marrs.
Above Black, (Author ??)
Most of these books do not attempt to make any sensational assumptions. They mearly state the facts on this issue, and how it has been handled by the Military and intelligence communities.
One key FACT I've found in reading these books is this. You don't tell your deepest secrets to Elected Officials. This includes Presidents!