How deep is your belief?

Just read about the list of early attempts of inventions, often leading to disaster. Yet none of these guys is famous nowadays (surely due to their tragic failed attempts). And all/most of them did believe we could fly and never doubt, never quit. These guys bet with their lives!
Only now do I realize how rough is the path of invention and how many failed efforts had to be made before we reach to a stable result, similarly to bitcoin's build-up evolution last 50 years...

What is the strength/depth of your belief?
(Do not mix it with how much will be tomorrow's price which is what everyone asks these days inferring lack of a core belief)

Link 1: https://getpocket.com/explore/item/13-inventors-killed-by-their-own-inventions

Wider range Link 2: https://en.wikipedia.org/wiki/List_of_inventors_killed_by_their_own_invention