[Lumen]

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For Obito, again, most of his rage was planted. By Madara that is. By telling him that Rin was killed and whatnot, he triggered the one thing that Obito cared most about. Leading him were to his insanity. 

Sasuke was alright before he left the village in search of power, which lead to him killing Itachi, which again; lead to him becoming insane. Not to mention that he thought he was doing the right thing but when he found out why Itachi did what he did, he then became mad at himself and the world that his brother was now gone, the only thought to be left Uchiha in the world. So it all stacks up.

The only reason Tobirama said what he said was because they were opponents. I'm sure Madara would've said the same regarding the Senju clan. They had both killed thousands of each others family and they only had left was negative thoughts regarding the other clan.

What you said about Tobirama is invalid. He viewed the Uchiha as friends, rivals, family and foe. He stated that there are no clan in the entire world that treasure love more than the Uchiha, and it is this specific thing that drives them over the edge. Madara knew this and did it to Obito, which made him lose his mind and refer to the real world as; "the fake world" believing that the world he would make would be the "real world". (That is pretty much insanity.) He later changed though. Sasuke was obsessed with revenge for his loved family, which drove him over the edge, but only when he found out the truth, again because of love. This is what Tobirama referred to, they are good people, though they break easily, and lose control. 

Tobirama even stated that there were some expceptions, like Kagami Uchiha. So a majority of them are unstable, though not all. Madara also had nothing but praise for the Senju as seen when he fought the Gokage. Referring to Tsunade as "ugly" since she brought shame the her family name by being weak. (He directly states that the only thing uglier than a weak person is a weak Senju, showing that he had respect for all Senju, just Hashirama specifically as well.) 

The Uchiha are nut jobs.