SpaceX's first three rockets failed. The fourth reached orbit with the company nearly out of money. Today it lands boosters and reuses them, and launches most of what goes to orbit. That alone is hard to argue with.
Tesla pushed the whole car industry toward electric faster than it wanted to go. His habit of questioning every requirement and deleting parts is genuinely useful thinking for engineers.
He's also made a lot of reckless public statements, and how he runs X and treats people has hurt his reputation badly. I find it hard to admire him uncritically and hard to dismiss him.