Finally I found the reason. Here is a quote from Nietzsche’s sister:
The days of his youth — of his carefree, merry gamboling — were over. Hereafter he was all solemnity and all seriousness. ‘From these early experiences,’ says his sister, ‘there remained with him a life-long aversion to smoking, beer-drinking and the whole biergemütlichkeit …’ He maintained that people who drank beer and smoked pipes were absolutely incapable of understanding him. Such people, he thought lacked the delicacy and clearness of perception necessary to grasp profound and subtle propositions. (via Noniclolasos)
Given the choice between being bored by Nietzsche or a beer I choose a beer anytime.