An 11th Reason why startups fail

Tim Draper the legendary (Rhino riding!) founder of DJF has an excellent blog post on the reasons startups fail. I'd like to suggest an 11th reason though, which we see frequently:
"The average cost of selling is too high."
In particular, we see many companies where the need to communicate complicated messages, over a succession of meetings, and maybe customer trials too, is itself expensive. This is then compounded because the proportion of those customers that convert is not too great, and they take a long time to decide to start paying. Finally when a proportion place orders it doesn't cover the cost of all that customer engagement.
It's a shame that 11 reasons isn't such a tidy number!