I surmised something similar on day 1, i.e. the interested audience will mostly be highly internet-connected early-adopter geeks. They will have heard about it very quickly, so it's not going to "go viral" and reach a much wider audience later on in the campaign.

The enthusiastic early adopters are more likely to pledge in the first few days and so a steeper than usual drop-off is likely. It's also a very ambitious target amount.