I echo that sentiment but oppose the positive adjectives tied to his motivation. Rather I believe can be at our best when motivated by our dark emotions towards positive actions: Grief, rage, madness.
Mr. Manjhi was compelled to this momentous thing after his world was torn apart by it. He persevered while the very people whose lives and whose children's lives he was improving mocked him. He worked for 20 years compelled by his demons and the universe is better off for it. I hope destroying the mountain gave him peace.
I dunno. Grief, rage and madness can only take you so far. The care and compassion for other human beings is what makes you continue. I don't think he'd be able to hammer down such a path for the duration of 20+ years unless he was deeply passionate about preventing the same issue for others in the future, even if they mocked and taunted him at the time.
It feels like an Orphan-crushing machine[0] kind of story. It's amazing he achieved that but he shouldn't have needed to. Why wasn't there a road already?
You can be angry that the machine exists - and work to destroy it - but you can also appreciate people doing the work to stop orphans from being crushed. And you don't always have to do both at once.
If you only engage in the former... well, then orphans just keep getting crushed while you try to figure out how to stop it. And keep in mind the machine is much smarter than you, and has been doing this a long time and is really good at it and is always getting better, and is supported by various systems to protect it, and...
I know you put the numbers and everything, but I didn't quite grasp just what a monumentous task this was until I saw the image of the "path through a ridge": https://commons.wikimedia.org/wiki/File:Link_between_Ghivra_...
It is absolutely bananas (and wonderful!) what a single human can achieve with love, passion and determination.