What we need are a few missions to demonstrate insitu resources.
I foresee the need for 2 missions. First would be sample return where the return craft makes its own fuel. The second would be a small biodome full of gerbils or something, that would survive for a few months. (order not necessarily important)
Once its demonstrated that it CAN be done, people will go for it...maybe, well not many people would go if there's no guarantee that they can survive without supply drops.