I wonder how many profitable customers could be had in that time.
Well, no. We couldn't.
The "customer" wanted specifically to see how we did what we did, in order to copy this. It took me a while to figure it out, but I did, and we wound up walking away from it. Partner was angry, but it was absolutely the right business decision to terminate the interaction.
PSA for any small startup firm with real differentiation: BigCo will, absolutely, positively will, try to see if they can replicate your value on their own rather than buy from you. Patents won't stop this. Pretty much nothing will, apart from an architecture and implementation that they don't understand. They will mess with you. Approach with extreme caution, and be prepared to cut bait quickly.
Can you elaborate? Is this because they'll infringe anyway, then use their big legal budget to game the system?
Corporate parent trolls eat them up and sue.
There are publicly traded companies whose sole means of profit is patent law suits.