Not to be flippant but who cares? People don't know there's an option. I've run Graphene for years and will gladly pay a premium for it. Beyond the bolstered security the battery life is exponentially better than a default Android device because of all the constant background traffic that Google doesn't allow any control over that you instantly have a choice with on GrapheneOS.

And as soon as you start showing these things to people they do start to care and ask how. So the fact that the mainstream is ignorant and doesn't care enough yet doesn't matter because it's very likely a much larger segment of users will care when the tech evangelists they trust stop using IOS and Google Android. That's how these things started and that's how they could very well play out in this scenario as well.