I get a lot of criticism for telling founders to focus first on making something great, instead of worrying about how to make money. And yet that is exactly what Google did. And Apple, for that matter. You'd think examples like that would be enough to convince people.
What I tell founders is not to sweat the business model too much at first. The most important task at first is to build something people want. If you don't do that, it won't matter how clever your business model is.
The Summer Founders Program fixes the common problem with working at a startup, which is that it's very lonely. You do nothing but work and sleep and no one understands the situation you are in, and friends don't know why it takes three days for you to call them back.