Quoting Wikipedia:
Führer was the title demanded by Adolf Hitler to denote his function as the head of the Nazi Party; he received it in 1921 when, infuriated over party founder Anton Drexler's plan to merge with another antisemitic far-right nationalist party, he resigned from the party. Drexler and the party's Executive Committee then acquiesced to Hitler's demand to be made the chairman of the party with "dictatorial powers" as the condition for his return.
What I don't get is why did Drexler submit to Hitler's demand? Hitler's demand is pretty much for Drexler to give up his party to Hitler. What happened that made Drexler did that?