622 chapter discussion contained a post by an awesome forum member saying sasuke wos likely beibg groomed to be a spare. While that in itself would be its own discussion it does fit very nicely and answers many motives for our "villains".
Anyway, let's roll with that theory and other stuff.
Izuna, madara, and hashirama were all on the same page and had same hopes and dreams.
Izuna loved madara very strongly and wanted to protect his brother. A circumstance arises where izuna chooses accordingvto his own free will to give madara his eyes because the outcome would be izuna protecting madara. Hashirama is privy and acknowledges the sacrifice. Madara cannot cope, realizes that if izuna had to sacrifice himself then all the efforts forming an alliance and village in order to stop brothers from having to die is a failure. He decends into darkness, not appreciating nor seeing what izuna hadvactually done. He could not find meaning in izuna's sacrifice yet hashirama did know its meaning.. this would be typical platform by which hashirama would appear patronizing if he attempted to ever talk about it with madara.
The core of that situation runs deep in almost every main relationship taking place in konaha.
Yahiko and nagato
Jiraya and oro
Itachi and sasuke (nearly 100%identical in circumstance feelings)
Also extremely important is obito and kakashi..
All of these contained a figure failing to find meaning in a death, resulting in them chosing the dark path, wheras the will of fire gas all the opposite in its path of "light"
Obito acted like izuna by saving kakashi only to reflect madara when presented with the hardest "why" challenging his decision.
This plays into the uchiha massacre for obito's personal reasons, we need not discuss itachi's angle in it here..
Obito would have strong need of exacting vengeance upon the uchiha since the clan tradition of sibling sacrifice is a meaningful aspect behind "winners and losers ", obito at first seemed only interested in a stock of sharingan but with what we now know about him, his state of mind and heart had very twisted reasons to wipe out uchiha for its role in causing the need for an infinite tsukiyomi, the clan intentionally breeded losers for those it considered winners. Their core mission and reason was the exact injustice obito wanted to erase. It'svalso why itachi would agree to cooperate and work together. This is the only way, imo, for the uchiha massacre to make any sense at all and tie up all ends and their many reasons for contributing wittingly or otherwise, to erasing the uchiha. Keep on mind not all involvements or reasons meed be immediately direct in nature while some party's were indirect or ignorant of certain things.
Asuma team is the only example of the protected finding the true meaning in the sacrifice of the "protector".
Madara abandoned the village and the dream because hashirama allowed izuna to sacrifice himselfvyet madara took it differently. That was the basis for opposing from then on, a once yet former friend who allowed a sacrifice while claiming to bring answer to keep sacrifices from ever having to happen.. a world where rins die and izuna's die .
The only thing left to answer is..
What were madara's policies afterwards that earned him "sympathizers"? Was it the next level of a cyclevof hatred? I believe madara then began gaining uchiha support for the idea of what was later practiced bybpost yahiko akatsuki; to endwar and suffering by monopolizing tailed beasts and military power, making war a dangervso amplified that people would fear it forever. The uchiha wouldbe the mostvsuitable clan for harnessing tailes beasts and using themvas weapons, that is thevsecret rolecof sharingan, uzumaki and senju tailed beast methods trwatvthem differently than weapons.
Madara's motives for turning evil, justification for his hostilityvto hashirama and leaf, the platform for both flavors ofvakatsuki kusyice, a sensible political cause to warrant "sympathizers" (hashirama didcthe exactvopposite of whatvthosevsympathizerscwishes were, shared tailed beast power )
The flow and ability to gracefully segue into obiyo'sordeals asvwell as nagato's.. and especially sasuke's.