Details of what I can remember... Story starts off with describing man that has no moral limitations. He does whatever is necessary to succeed or survive. He signs up for a failed space mission where there are not enough room in the escape pod to fit all crew members. He takes it upon himself to choose who to get rid of.
They get back home and is prosecuted and has to talk to psychiatrist whom he manages to seduce. Story progresses along where he moves up the ranks in a number of difficult situations and ultimately becomes leader of the world. Late in his life a mysterious alien ship is detected heading towards Earth. It is later uncovered that the ship is actually heading towards the Sun to trigger its destruction.
As a last message to Earth, he instructs any survivors to take any means necessary to survive through this catastrophe. And in 10 or 100 generations, bring themselves back up again to find whoever did this an exact their revenge.