This is actually a rational explanation for this. Perhaps Elon wants to sink the whole industry until he can actually build a self driving car like Waymo's.

Perhaps he's bad at his job

He wants to break trust in the whole industry by giving Tesla a massive black eye, undoubtedly hurting their stock and sales significantly, in order to, later, create actual self driving cars into the market that he's already poisoned?

Totally rational.

Elon's drug addled brain doesn't make rational decisions.

Well, admittedly maybe I should have said "rational to Elon on Ketamine"