There were actually a few times where it was a sensible buy. Right after they got the Model 3 production line going, for starters. Right now it's being forced up by the stupendously large amount of money being injected into the stock market, which can't go on forever no matter what Tesla does.

Not saying I'd bet against them, mind you. The market can stay irrational longer than you can stay solvent, as they say. And even so it's probably not too bad a bet if you could hold it for 20+ years, but it's going to dive before it rises again.