Do I believe in aliens? Yes, in the sense that I think its likely there is life on worlds other than Earth, including species at least as smart as humans. But I hesitate to believe that aliens were responsible your experience with the "white glowing dot" that “moved at a slow and steady clip"... You’ve mentioned that your guide briefed you on how to recognise “airplanes, helicopters, drones, military aircraft, satellites”. Did she also brief you about balloons and blimps? Lighter-than-air devices generally travel more slowly than planes, and they don’t jitter about like helicopters… Could the dot’s glow have come from a propane burner, used to produce hot-air? You mention the glow becoming brighter after you shone a laser at it. Could that have been a burner being adjusted up by humans on a balloon?