I read recently that nearly 50 percent of seed-funded companies go under before reaching a Series A round. I don’t know a lot about some of the major reasons why seed-funded fail to grow and reach another round of fundraising.
For larger context: I did a lot of digging and the best numbers I could find for Y Combinator-backed startups was somewhere around a 96% fail rate. By "fail" I mean the startups ran out of money or declared bankruptcy or just disbanded. Remember, that's how the VC model works. They need only one or two out of a hundred they back to pay out (but also keep in mind that their desired goal is for that startup to get sold off).
Not prioritizing revenue and falling in love with the product. Sell "good enough" now.