>>212939631
He wanted to carry on his fathers ideals that humanity was destined to grow beyond needing Earth(Newtypes are the personification of this ideal) but the events of 079 and Zeta blackpilled him over time. He eventually lost hope that humanity could grow unless forced.
It's not outright stated but I believe losing Kamille played a big role in it as he was the exact kind of next generation he wanted to see lead humanity into the future.
https://www.youtube.com/watch?v=KQMz7YHPIiI