While I don't like Musk as a person, I think that Spacex being the single largest launch provider in the world proves that he isn't just a con man. I also think that Falcon 9 counts as important technological progress, with its reusability. Starship also counts, even if it ends up being far more expensive than he says, it will still be incredibly useful for space exploration.

I don't know much about his other businesses though so those might be garbage, but Spacex is not a scam.