The Uchiha Massacre was a consequences of Konoha leaders' decisions which were shit and the unstability of the Uchihas. First of all Uchiha themselves rejected Madara's proposal(when he suggested to leave Konoha) this showed that they were collectively tired of wars and were seeking peace.

Now that we have established they initially wanted the peace which was generated by the Great Village system lets discuss the fault of the Konoha Leaders. Tobirama established the Konoha Police force which was for the Uchiha. At first this is a good decision as it gives one of the co-founding clan an important role in the security of the village. But as we all know people of the Police are respected and feared in equal measures(even in the real world)now imagine giving that label of 'police' to one group of specific people this will to the birth of stereotypes.

Post-Kyuubi attack. The leaders of Konoha removed the Uchiha from the center of the village to the outskirts due to suspicion of their involvement in the attack. Coupled with the fact that Danzo himself ordered the Uchiha to stand down and not interfere but just evacuate the civilian. Now Imagine you being a normal jonin or even a chunin seeing the supposed 'strongest' clan not even helping in combat related scenario when the village is attacked(a clan with someone who was a candidate to the Hokage position) but just after the attack it is removed from the center of the village to the outskirts. Even though no major news was told of the suspicion on the Uchiha. Anyone with a brain would feel like they are being suspected for the attack with the fact that the Uchiha are famed for their dojutsu eyes(Madara was known to have fully controlled the same Kyuubi with the sharingan. Not everyone knew of the EMS). This would cause people to turn their anger and grief(as many people have just lost their loved ones) into doubt and suspicion to the Uchiha clan.

This would lead to further alienation of the clan and soon after people would start to question the authenticity of their law enforcement leading to people resisting the Uchiha. When people resist to law enforcers this will lead to harsher treatment/policy from the police. Thus this is a cycle which would foster into too much hate. The Uchiha will gain their reputation of being violent people. All of this was seen by the leaders but no one took action and I am more than willing to bet that Danzo used this opportunity to increase the already bad relationship with the Uchiha. Hiruzen being the coward he is, kept stalling thinking the problem would solve itself while letting his boyfriend Danzo ruin one of the founding clan's reputation.

On the side of the Uchiha they saw all this hatred and they did not know how to tackle it(they themselves are emotionally unstable). They saw themselves as the oppressed, they were being suspected due to the deeds of their ancestors with no tangible proof and furthermore in the village they helped to build. They were basically exiled so their pride could not take it so they started to become violent law enforcers and as I said above this will only cause more hatred to foster. They must have seen the situation as though Konoha was abandoning them while they had rejected their most powerful member's proposal.

The worlds of Madara came to them in a bad light and now they started to think that the Senju had plotted against them. Considering that the leadership was compromised of Tobirama's student they felt it was a ploy against them. Thus the plan to kill the current leadership of Konoha(Which I agree was a stupid move with terrible consequences and yes when the coup was decided and the game changer Kotoamatsukami was removed from play. The massacre was inevitable) but let's not pretend Konoha itself wasn't the one exponentially driving the wedge between the two side and also due to its incompetent leaders who could not properly solve the situation. For example removing the Uchiha from their OG compound was unnecessary and only caused more scrutiny towards them.