David Rusenko was a college student when he applied, at the last minute, to Y Combinator in 2006. His startup, Weebly, made a web site builder. At one point they came within days of running out of money, but they survived to be acquired by Square in 2018 for $365 million. Now David runs a fund, Leap Forward Ventures, focused on climate change. He has spent his whole career in startups, and has seen close to everything that can happen.