John Snow had evidence, and a hypothesis that could be tested, but no one took it seriously. That's a lot more than UFO believers have.
UFO 'believers' have - since very recently - videos released by the US military in which they say 'detections of this object were confirmed by multiple sensor platforms' and 'we cannot identify this object and have no speculation as to its origin' or whatever the exact wording is.
You know what I mean, the 'tic-tac' video. The narrative provided with that video confirms that the object/objects were detected by multiple types of sensor (visual, infrared, radar) and by multiple sensor platforms (aerial radar, aerial infrared, ship-based radar) and that the detections correlated.
With those releases the the UFO landscape changed, to wit, the US military is now a 'UFO believer.'
You're free to ignore all of that and assume it's aliens but doing so is just superstition, not reason.
[0]https://en.wikipedia.org/wiki/Pentagon_UFO_videos#Potential_...
[1]https://www.thedrive.com/the-war-zone/drone-swarms-that-hara...
Stating you don't know what an object in the sky is , is a completely reasonable thing to do.
Making the claim they are alien ships without any proof is not