You misunderstand me. I am saying that I don't think this user story requires a standalone email client. You could replicate most of the key value propositions

You misunderstand me. I am saying that I don't think this user story requires a standalone email client. You could replicate most of the key value propositions (if not the specific feature implementation) as extensions to Chrome and Gmail. That would be both a feasible solo dev idea and a more reasonable $5-10 a month rather than $30. Sure, throw a couple hundred million at the same problem and you'll overbuild it into a monster. But that doesn't mean it's the right business model.