I've got two rather fluffy justification to myself that I use. The first is rather simply that I want to support someone doing something that's cool, but of such a nature that it is not financial viable in a free market setting. Straight up patronage basically.

The second is that in addition to the whole pre-order thing I'm using my money to send a message to the market at large. Basically its my way of saying I want these sort of products/companies to exist. Even if this group of people fail to deliver, hopefully other will see that there is a market there and someone else will pick up where this particular group failed.