Getting user feedback from insular communities in competitive markets

Hello all, I've slowly been building my app in a vacuum, with some friends cheering me from the sidelines. Though their support was useful for the build phase, their feedback on the product is severely lacking. I'm trying to leverage both my network and insular communities made up of my target customers (financial analysts). Notoriously, these communities are hard to broach. As a former analyst, this is rational behavior: they get marketed to constantly for products. It's been hard to get any traction.

I'm wondering what tactics others have used to get in front of really skeptical users. For example, I'd love to use some of the tactics in "Deploying Empathy" on Reddit, but these communities have strict self-promotion guidelines.