Expanding on that, just because you don't understand what problem it solves, why people would want to pay for it, or why VC's believe they can profitably invest at a given valuation, doesn't meant that any of them are wrong.
It just means you don't understand from someone else's perspective. So when you say "This is one of those cases where a good dev could likely build a clone in a month. And it hardly needs constant updates." - it's coming from a place of ignorance to the other people's problems and their scope.
> Perhaps you could enlighten me to the problem that Postman is solving?
A quick glance at their homepage helps with this. "Build APIs together" and then the value props go on with "Postman simplifies each step of the API lifecycle and streamlines collaboration so you can create better APIs—faster."
So Postman is about the collaboration and process of building APIs. Not about a curl gui. That's an expensive, big, valuable problem space.
Obviously dropbox has a sharing problem to solve, but I honestly don't see what your post adds to the discussion. Perhaps you could enlighten me to the problem that Postman is solving?