Bootstrapped from YC rejection to $35m from Sequoia Capital in under 3 years

I was reading about YC rejections when I came across a company who wrote on HN about trying to hack back in after a rejection. They failed:

https://news.ycombinator.com/item?id=20224157

But a scroll down their blog revealed a 1 year rise to $1m ARR and now this investment.