Funnily enough, PCP is a drug that is very similar to Ketamine, but has a very different reputation.

Whenever someone sees someone in full-blown psychosis walking stark naked on the side of the road, PCP immediately gets the blame. In reality, both drugs have the same psychosis potential.

It's not an immediate thing. Heavy users will just start feeling confident and motivated. Little need for sleep and a spring in their step like they are light as a feather. As the heavy use continues, this can spiral into mania, delusions of grandeur, detachment from reality and paranoia.

I have no way of knowing how much Elon uses, but it would not surprise me if he is treating himself with consistent low doses of ketamine. I wonder how his memory is, that would be a pretty good tell.