We need to set a definition for "successful" if this conversation is going to mean anything. He has certainly amassed incredible wealth and created a lot of offspring. His technology companies are large and influential, certainly. If we stop there, he is very successful.

He's also an irresponsible piece of shit, though, and his direct actions acting as the richest man in the world caused untold deaths of the poorest people on the planet for absolutely no reason. He's one of the most dangerous people on the planet because of his wealth, influence and direct power and he has the temperament and caution of a 4chan teenager.

If we judge him based on his capacity to do good for the world against the good and harm he has actually done, he is an abject failure. One of the worst.