I can throw out a couple of answers off the top of my head:
1. They may have already front loaded beforehand 2. Many people will not buy in until there's solid evidence of earnings. SPZI, after all, is still a pinkie first and foremost. You assume that all traders have the same risk tolerance. 3. People're selling throughout summer. Perhaps they may have taken the time to buy already. 4. Being excited at the product doesn't necessarily mean that they'll buy into the stock as well.
Just wait until launch. As I said earlier, PRs are needed as a catalyst.
Who says those who have seen the demo haven't bought? The CMF says someone has been buying. And it sure doesn't seem to want to go down. So a better question, IMO, is why does no one seem to be selling?