How do capital and customers differ in their importance to a startup?

According to Kevin Hartz, customers provide the most nutritious sustenance for startups, while capital is like sugar - it gives a quick energy burst but doesn't sustain the business long-term. At Eventbrite, they initially bootstrapped for two years focused on customer-centricity, which helped them build a solid foundation. When markets collapsed in 2008-2009, companies bloated with capital failed, while Eventbrite thrived by being capital efficient and customer-focused. This approach ultimately attracted investment from Sequoia Capital when they were in a position of strength rather than desperation.