In this thread, we've been led from 500K/yr to 50K/yr to 20k/yr (5k for 3 months) and now back to 50K. I think most everybody has loans, credit card debt, and a mortgage. But if you're sufficiently young enough and want to have a startup in the next 5 years, don't get a mortgage, get a normal job to pay off the student loans and credit card debt, and save up some money.
I seriously doubt pg actually expects people to do YCombinator with $0 saved up and tons of debt and live on 5k for 3 months. Or worse, with an illness or surgery that needs to be done. Get all that out of the way, pay off your loans and credit card debt, and save up some money by working corporate. Plus you'll have experience, good references, friends, and maybe good contacts from working at a company.
I used to think I was old when I turned 21 and 22, but if you're 25 or 30 when you start a startup, that's fine! But before you work at corporate, make sure you do your own startup with customers and everything in college so when you're hired, you're respected and management wants to hear what you're saying, rather than HR placing you in a "trainee" program like two high school acquintances my age will be at the same company for the next two years. That gives you credibility from your coworkers, experience leading your own project from your startups, and a degree you've been able to pay for. Maybe you could even get a Master's degree in Business or Computer Science that the company will pay for while you work.
This means you won't be a "millionnaire by the time you're age 25" like everybody our age who's heard of Bill Gates during the late 90's has wished for, but getting out of debt by the time you're in mid-twenties is the new "being a millionnaire", with the cost of everything these days.