When I look at the early history of flight, I find it so fascinatingly absurd that inventors simply jumped from high cliffs on the *promise" that their invention would work. No one else had mastered human flights. Designs similar to theirs had failed in the past.
Some people get a bit nuts when bitten by the "personal flight" bug, even to this day; people with no great knowledge of aerodynamics or mechanical engineering are always hopping in some homebuilt ultralight and killing themselves. People lose their rationality, chasing a dream.
Franz Reichelt warrants a mention at this juncture. In 1912 he was so invested in the success of his parachute invention that he refused the pleas of his friends to test it with a dummy and simply jumped off the Eiffel tower, to his death. Rather shockingly, Wikipedia has video footage of this event:
And the wright brothers were not the first to fly. They were the first powered flight. People had been experimenting with kites and gliders for a thousand years. It wasnt a "jump off the cliff" moment more than an incremental breakthrough after many years of struggle.
There are many disputers. One thing they all have in common is a complete lack of evidence. Ader, for example, pops up 17 years later saying he flew. But he's got no airplane, no witnesses, no photo, no followup - just a drawing. Even worse, he claimed an altitude of 3 inches - about what you'd get from going over a bump or a gust of wind.
And does anyone really believe someone would toil away for months/years, build an airplane, make one flight with it, not tell anyone, dismantle and trash the airplane, and forget about it?
Nope. I'd be flying all the time showing off my creation.
1. years of notebooks where they logged their ideas, progress, data, designs, etc. The notebooks clearly betray their understanding of what they're doing
2. a clear photograph of their first flight (a contender for the greatest photograph in history)
3. witnesses
4. a stream of prototypes leading up to the first flight
5. a stream of improved machines after the first flight
6. many demonstration flights
7. the original machine was preserved and sits in the Smithsonian for anyone to examine
8. exacting replicas have been built, which fly and exhibit flight characteristics that match what the Wrights described
The other claimants have literally zero of any of these.
Yet these people just...jumped.
Talk about commitment and belief!