He’s not a billionaire because he is cheap. He’s worth $200 billion or so because he is a great allocator of capital.
The concept is not that hard and everyone should know the numbers by now.
He made $150 M on PayPal/X merger.
$100 M into Tesla as early investor (not actually cofounder)
$40 M in SpaceX based on the ideas of his college roommate Aleo Ressi
$10 M into Solar City.
He grew each business. Solar City was acquired by Tesla to save face.
Growing Tesla had nothing to do with personal cheapness.
Growing SpaceX had nothing to do with personal cheapness.