Same here :)
It flies in the face of our accepted scientific knowledge and reason - but what keeps me interested is the unexplained fact of verifiable sightings by trained observers such as police, pilots and radar operators. Too many of these have witnessed unresolved UFO phenomena and activity, for one to reliably dismiss their reports. So, the questions remain.
The secrecy and denials which I'm referring to, exist, imv, for one (or both!) of two possible reasons:
1. Black Budget weaponry and aircraft
2. Knowledge of the actual existence of real non terrestrial entities, bound secret by unwillingness to publicly acknowledge neither their existence nor the possible fact that Govts cannot "control" them.
Such acknowledgement risks both unacceptable loss of face and possible public/religious panic and critical destabilisation of our acceptance of civilisation as we know it. After all, we "rule" this planet, supremely confident in the knowledge that no other being has ever "tamed" us.
Now, imagine the psychological shock to our species if we no longer had that confidence ? That's why, imv, Govts won't ever spill the beans in full.