It’s not really so much a conspiracy theory as a thing that he outright said.
https://www.jalopnik.com/did-musk-propose-hyperloop-to-stop-...
That link denies the conspiracy theory?
> “Or did he just have an idea and blurt it out," I asked Vance. > "I'm 99.9-percent sure it's the latter," Vance tells me.
Also that to scapegoat Musk for killing the California train when California was perfectly able to kill it itself:
> Vance then brought up a valid point: "In all this time we've been talking about high-speed rail, there's still almost none that's built....
He can take out a full page Wall Street Journal ad tomorrow that says “I created hyperloop to kill CA HSR” and it will have no effect on the fact that CA HSR’s failure is 100% the fault of CA’s own dysfunction.