I can't help but have a very negative reaction to this, not necessarily at the author, but at the startup ecosystem as a whole. These are posted as "lessons" as if they were difficult to learn, when this really should be labeled "things no responsible person would ever not know before even considering raising money." Of course you should be self-critical of your product, of course you should test with real customers, of course you need a technical co-founder, of course you should pick a market with a bigger niche than tech-saavy-foodie-cooks-in-major-cities. Every mistake was classic marketing grad trying to do startup things in a bubble environment. These are the types of "lessons from my failed startup" that have been written a thousand times before. I fear over-exuberant and irresponsible entrepreneurs will repeat these mistakes for as long as startups exist.