Almost correct, the cardholders pay upfront, however the financing of the plane is completely done by netjets, upfront as well.
It is different on the owner side, they actually buy a piece of the plane, so they are the ones financing the planes.
So NetJets original plan to sell fractions was great, almost no financing required great stuff, the last crisis however decided them to make it more attractive to the market and started offering cards. Which is a great tool, but mostly used to persuade people to become owner. This pratice has gotten out of control and the ratio owners vs cards is wrong.
Therefore NJ is needing a lot of finances to keep the thing running....now Buffet is needing all the cash for his bet, then there might not be cash enough left to keep the operation running....
Together with the unprecedented slowdown in sales it might be wise to sell the business to whoever.....
So I see a lot of problems for NJ in the short (1 to 2 years) future.. (too many pilots, postphoning of aircraft, problems financing the operation, aircraft sitting on the ground long term, etc)