"f he opens it up to everyone with no restrictions he will face tremendous churn. Plus 98% won't see any value at all and will bash the product online perhaps discouraging those who would benefit from even trying it."
Yeah that's not a valid excuse.
There are innumerable product categories where such problems exist.
Every product you could imagine is more useful for one group than another.
He is creating a MLM-ish exclusivity club, a bit like with Clubhouse (VC's were early participants, bringing in people who wanted to be in that circle).
And: "The overall market is so large that even a tiny sliver of those users who willing pay for the product is a pretty large market. " is one of the biggest pitch fallacies. Tons of young entrepreneurs use this justification in their pitches. There can be reality to it or not.
The obvious 'hustle' is blatantly apparent right in the name: "Superhuman"
He's literally making a direct appeal to the egos of successful people, who think they are a bit better than everyone else.
It's a hustle to sell something into the most lucrative market of 'monthly revenue' from people who can afford it.
It's a bit like Forbes magazine or something.
I'm sure it has some neat features and it may not even be priced wrong - but the marketing is cheezy.
It's also an example of how so many smart people lack self awareness, how people think they are immune to advertising, even people who design marketing overrate their ability to resist influence. The Ego is the great deluder, it's almost impossible for the Ego to reject incoming information that embellishes it.
I think tech people are among the worst of this - because you have high performing, very intelligent people, probably prone to thinking they are 'better' (in some ways maybe they are), but it's also an industry 'the furthest away' from marketing and communications, with basically no bridge of intuition. The language of tech is completely unhelpful in terms of understanding the language of communications.