Even if it doesn't seem obvious, there are two motives of clubs, it's to win trophies and to make money. It now depends on what they focus on and how they still manage their resources to achieve the two for themselves. Borussia Dortmund is stylishly achieving the two at the same time, and I will not blame them for that, though it's obvious that people have been talking much about it. Yet, they manage to always deliver as they always have a voice in the league and a top rival of any winner of the league.
Dortmund chose their strategy and they prioritize money than titles. It helps their club to have good finance in latest years and are competitive in Bundesliga as well as regularly participating in Champions League. However, ending seasons with a runner up position caused a lot of regret, disappointment to their players and fans. Honestly, if their players and fans can make choices, they will choose to win titles.
They've been second in the last 5 leagues and ended up being third in one. This is not so bad and one day they will get it right and be the winner.
They are a most popular runner up in Bundesliga in last 11 years and we know since a transfer to Dortmund, Marco Reus has never won Bundesliga with Dortmund. It is big regret that Reus deserves to win one Bundesliga trophy and he is counting down last seasons before a retirement.
Bayern Munich is not a club you could just win anyhow even without selling good players, Dortmund would not also sell all their good players, only that they would have had their chance on Bayern last season if they are better serious enough.
Bayern Munich are a strongest club in Bundesliga from strength on field to their power in finance. They use money to buy best players from their domestic competitors and reduce chances for those competitors to win against Bayern.