1. Backing this project is using your dollars to "vote" for this device to exist. It's not as unimaginative as "buying a phone", it's about helping to establish a new mobile device os as a real alternative.
2. This type of fundraising rarely follows a linear growth curve, so there's nothing to infer about the ultimate success of the project by projecting that way.
I have not backed the project, and I'm not sure if I will, but I really appreciate that others are trying to make this happen.