On the one hand, it's great to share empty supercharger capacity with all EVs, making EVs generally more attractive - and of course, more money for Tesla from charging maybe = even more superchargers.
On the other hand, the biggest challenges with an EV vs. ICE car are (obviously) range and charging. With this in mind, the supercharger network, and supercharger capacity generally being ample, probably rate pretty high when choosing a Tesla.
It mightn't take many instances of having to wait to charge due to non-Teslas filling up supercharger capacity for that USP to fade and the Tesla ownership experience to be significantly damaged.