The interviewers disbelief that food money is so important reminds me of my first experience with startups. When I was an undergrad I worked for a doomed startup, and I remember with all the various government and other sources of support out there, absolutely noone was willing to pay for rent or food. I mean the money had to specifically be for hardware or the like, but the biggest hurdle is the day to day money. Even living with your parents you need to buy some of your own food. It's not in the least bit trivial.