The Gabon international left Dortmund in January 2018 for a lucrative move to Arsenal.
And Watzke has laughed at Aubameyang spending the last two seasons watching the Champions League on television.
"Of course it is hard to keep a player in the face of such sums," Watzke told Suddeutsche Zeitung. "Some go to clubs because of this money, where they have not played Champions League for years.
"Pierre-Emerick Aubameyang, who plays great at Arsenal, will probably be warm-hearted when he looks at his bank account, but on Wednesdays, will be saddened when he has to watch the Champions League on television."