That's really interesting and scary. It seems that you can doom yourself quite easily (and unfairly) by just picking early investors who for some reason don't do subsequent rounds. I was a founder at a company that raised a few $ million, from a single fund. Unfortunately there weren't a "top tier" fund and subsequently decided that tech investments in general weren't a good idea for them. We had some interested parties for a next round, but when they didn't invest we also lost all the other parties. Another company funded by the same fund had the exact same situation. Hard lesson learnt: if you don't raise from a top tier VC it could bite you hard!
I estimate you folks probably have on the order of 200k~ users and 10k~ brokers on the platform judging by the numbers of the raise~
No graph, no traction, little future.