I took Gecko to mean that "greed" is merely self interest in the Randian sense. It motivates mankind to advance, as the quote states. It has nothing to do with "greed" as the lefties use the term.
Gecko was portrayed as a dick in the movie. Of course that was the point of the movie. To demonize capitalism and capitalists.
But, he was absolutely right. Greed IS good. Especially if you understand Ayn Rand.
I will chalk up your misunderstanding to a reflexive reaction to the word "greed." It is a conditioned response.
Ayn Rand was an intellectually brilliant woman whose larger life was imbalanced and her philosophy severely diminished by her atheism and self-centeredness.
Reading her books is like spending a lot of time looking at a two-dimensional surrealist painting.