A month after dropping out of a Stanford University PhD programme in the spring of last year, Demi Guo and her friend Chenlin Meng had raised $5mn for their start-up.

The app they created, Pika Art, uses AI to produce wild video effects and threatens to make at least one aspect of traditional video and film production a thing of the past. Within a few months, it had more than a million users while the two founders, both aged 26, raised $135mn in just over a year.

Their story would be exceptional anywhere outside Silicon Valley, and is rare even there. But California’s famed network of mentors, innovators and investors helped make it possible, they explain. With investors, “there was mutual enthusiasm from the start”, Guo says, explaining that they “brainstorm ideas with us, help with recruiting and more. If I run into a problem, I can just text them, and they’re immediately helpful.”