Questionable sales? Most of people who bought #1 can`t be counted as fans. Half of "fans" drop books after #1 and never returns. Some buy all #1 for collections and even do not read them.
His 13th issue still sold much better then Extraordinary numbers.
Also compare how much profit marvel got from 13 issues of UA and Extraordinary. Sincerelly doubt that 80% of lost readers means smth here.