Huh, true, if Tesla allowed other cars to use the Supercharger, then the chances of a Tesla owner arriving to a fully occupied Supercharger location (full of all kinds of car brands) would increase quite a lot.

But if Elon was serious about what he said about climate, and wanting to turn the car industry electric, he should do exactly that, so that more people get electric cars, regardless of the brand.

Elon is likely playing a longer game, just like the 'make a luxury car', 'make a better slightly cheaper car', 'make a normal car' line of thought where you hope to earn enough at each stage to make the whole factory, cell production, car, production, charging network, governmental interaction viable (economically, politically, environmentally, socially).

After it's possible to do it and not lose everything in the process, then you can do the "let's team up with the competition that didn't thing of this themselves"-game. Because that is what it boils down to: before the whole Tesla and Musk thing it was not really a thing to have a good all-electric car experience. Heck, even a good software experience wasn't available (in any car). It takes quite a beating for the other car manufacturers the get off of their collective asses en start doing something new. (and no, creating a different design isn't new, they have been re-designing for decades - new would be a paradigm shift or beginnings of a shift)