Why did Hitler take the power from Anton Drexler?

" At this time the organization adhered to a rather straightforward program-"Strikers, Bolsheviks, Jews, malingerers, and war profiteers were the enemy, and it was the duty of the workers to unite behind the war effort." (Payne, 135) However, after the disastrous conclusion to the war, Drexler's union, having changed its name to the "German Worker's Party," lacked any coherent program and was on the brink of collapse when Hitler inadvertently stepped into the picture.

from:http://www.novelguide.com/ReportEssay/history/european-history/hitler-and-dap