The fear is always going to be there. It's the dark side of having an "innovative" startup. If you can keep your head down and still get something done even through those periods, you're doing well.

I don't have experience in selling to BigCo, but here are a few ideas for potential research avenues.

Maybe there's a different way to "get to the right people" (which seems to be a big issue), or maybe there's a way to leverage the product itself to generate hype & interest from the actual users and have that spill over into a more convincing pitch.

Maybe a "magic little feature" is waiting to be added that would change perceptions at the corporate level. Or maybe the pretensions of interest they show at present are just sniffing around for a potential threat, acquisition, or knockoff IP, and you actually need to try for a different path into the market to get anywhere - even if it's well off the "beaten track."

There are more than a few stories where startup manufacturers end up going outside their area of focus and have to fund a complete vertical to the end-user, because other techniques failed and that was the only way to market the product. Which, of course, would lead to seeking investment.