Maybe I'm the odd one out, but I've been using Superhuman for years and it definitely helps me get through the 50+ emails that are awaiting me each morning significantly faster than either GMail's web or mobile client or Outlook on mobile. I'm quite happy to pay for it as it easily pays for itself.
Rahul has frequently personally responded to my inquiries about the product as well as recommendations.
They definitely don't deserve all of the hype or that high of a valuation, but I still think they are a great product.