On the live cast the presenter mentioned Boom have already secured ~130 pre-orders, including United Airlines. Not bad considering the Concorde anticipated 100+ orders but only manufactured a fraction of that.
Pre-orders are just wind until they're actually delivering product. It doesn't cost the carriers much to make the pre-orders. The calculation is that if it somehow pans out then they won't miss the boat, if the company fails then they aren't really out anything.
To be honest I thought Boom was an investor scam. I didn't think they would get this far. I still don't think they are going to build full scale production models and actually sell them, but I'll give them points for keeping it going. Moller kept his Aircar prototypes going for decades too though.
