He said it to his biographer: https://twitter.com/parismarx/status/1167410460125097990. He's also admitted that he thinks public transit is "gross": https://www.wired.com/story/elon-musk-awkward-dislike-mass-transit/.

There is non. This is only something anti-Musk stans cling to.

It literally is based on a screenshot of a twitter reaction on a half-sentence in one of his biographies, which at closer inspection has actually nothing to do with it.

Musk is a controversial figure to say the least. But the mental hoops some stans jump through to keep spewing their nonsense are astonishing.

Edit: Judging by the downvotes people really hate when facts like that are pointed out.

But you will be hard pressed to find any Anti-Musk stan who is actually willing to support his stand on this subject with sources. Wonder why...

The closest you will get to an argument is usually high-school grade name calling.