Ghetsis actually isn't insane. His plan made lots of sense, and didn't rely on "lol gods".
What he was is totally and completelly evil. He's probably the most irremedably evil character of the franchise. Not to mention, manipulating people into thinking random bullcrap by touching concepts you KNOW will cause them to think about it and taking advantage of them...? That is pretty realistic, it happens all the time in our world.
So yeah, what Ghetsis is is a jerk.