I'm a little tired of all this asking 'why' Elon Musk does things.
People who are that rich, with that much power don't live in the universe you live in.
There is no logical answer to the why.
They do things on a whim, because they can, because they get stupid, cruel, awful ideas and they have bought their way into an existence where there is absolutely no one around them who will tell them.
The only cure for this is a few years of poverty.