In the Memory Copy, Kurosaki Ichigo believed he had become this way because he was too powerful.
And that was indeed the case.
Because he was powerful and could not live peacefully among the weak, he had become so lonely.
This world was just that cruel. Those with Spiritual Power and those without it could not live together, nor could the strong and the weak.
Inequality from birth was difficult to forcibly blend together through human effort.
That was true for both the strong and the weak.
Because he was strong, he could not find companions he could speak to as equals.
In the world of Bleach, aside from Aizen, Stark, the No. 1 Espada; Zaraki Kenpachi, who restrained his own strength for battle; and Unohana Retsu, who found no equal opponent to slaughter and thus grew bored, were all the same.
They were all searching for equal companions. Yet during that long search, Stark and Unohana Retsu learned how to make themselves weaker, while Aizen never learned how.
But he did not accept that reality. Throughout that process, he searched for a new answer.
[If I cannot submit to equals, then I will make others follow me. I will become the god of this world.]
Wanting to become the god of the world was not an easy thing. It required at least two conditions.
Overwhelming strength, and dissatisfaction with this world.
Becoming a god was not the goal. Aizen's true aim was to change this world and make it operate in the way he believed was most correct.
The Thirteen Court Guard Squads had indeed rejected Aizen, but rather than rejecting his desire to change the world, they had rejected the means by which he sought to become a god.
Even Senjumaru's judgment that he was evil stemmed from