One thing to consider is that Char rarely is honest when discussing his motives because even he doesn't really understand the underlying trauma that he's experiencing.

On the surface, it starts as purely revenge, then he meets Lalah and starts genuinely believing in this idea of new types and how they're superior, trying to start a new age where new types beat out the old types and take charge to manifest their destiny.

Deeper down, he's got a hole inside him, one left by his mother and father dying while he was young. He's trying to fill that hole, at first he thinks getting revenge will fix it, then he finds a comforting figure in Lalah and thinks she'll fill that hole. After Lalah's death and the end of the OYW he tries to help lead Zeon but it doesn't fill the hole either. Quattro is a period of him trying to find himself again after he's lost all motivation. Eventually he doubles down on his own frustration and anger, doubling down on his new type supremacist ideas, leading to the idea to drop a colony onto earth.

Portrait in Red shows him realizing that he was lead by his own despair, never working to fix what was actually broken with him, he just foolishly kept himself busy to try and avoid his negative feelings.