I wasted $40k on a fantastic startup idea

This is the classic case of building a product that you hope will solve a problem instead of finding a problem first then building a product to solve it. The correct approach would have been to have those conversations with doctors before spending $40k to build the product.

I've made this very mistake myself but I was lucky enough to have enough runway to start over and talk to customers first then pivot the product to something that they actually need.

I call this the "I have an idea for a startup!" issue. You hear it all the time from family/friends. Where they tell you this great idea for a product they had. This is the wrong approach. What you want to say is something like "There is this really interesting problem that everyone in ecommerce is facing right now"

Uh no. He had a problem - how to choose a medicine - and built a product to solve that problem. The issue was that solving the problem isn't something people wish to pay for, not that the problem doesn't exist.

He had a problem, but then decided to solve a completely different problem. The process of an end user picking an OTC drug for a headache vs a doctor prescribing something are worlds apart. I'd personally love a site which compared all generic + branded medication available over the counter and ranked them based on some criteria. I'm sure there would be a ton of advertising and affiliate marketing potential for a successful one as well.