The short answer to your question is “Yes. The government is hiding many things.” For better or worse, competitive advantage is largely based on keeping secrets. Some secrets are kept in the open and some are kept by linking them with discreditable ideas or sinking them in a sea of discredited thoughts (or by passing them off as fiction). Some are just old fashioned kept secrets.
I’ve tried on just about every conspiracy theory one could think of for size. I keep a good number in my closet, but I’ve found the theories themselves matter less than the extent to which one believes they are true and how one decides to go about living as a result of those beliefs.