How can I go about raising money for my startup when the growth model is based on users and not revenue?

I'm working on a startup. The idea is well received. We need to raise money to get a functioning product. Advice on how to go about it is split in 2 camps. Camp 1 says: "Make a revenue model and show an investor how he/she can value the company and decide what their investment is worth in terms of percentage of the venture" Camp 2 says: "Don't bother about revenue, you'll make a barrier to users, users before revenue... get it out for free and blow up the industry" My question is: We still need money for development, how do I decide that $X is worth %Y for the camp 2 approach.