In Korean, 는/ㄴ댔자 is used to indicate that even if you carry out a certain action, a desired outcome will not be realized due to another counterproductive action.
Unlike 더라도, which can be used both positively and negatively, 는/ㄴ댔자 always conveys a negative consequence.
Examples of 는/ㄴ댔자
Health & Wellness
Even if you take medicine, it won't have any effect if you drink alcohol.
No matter how much you diet, if you don't exercise then you won't lose weight.
Even if you eat a lot of vegetables, if you eat them with salt, your health won't improve.
Language Learning
Even if you study hard, if you don't practice speaking Korean, you'll never be able to do it.
Even if you study Chinese, if you don't speak with Chinese people, your ability won't improve.
Lifestyle
Even if you eat breakfast, if the portions are small, you'll still be hungry later.
Even if you work in other countries, if you only interact with people from the same culture or nationality, you won't have the most interesting experience.
Conclusion
Understanding the 는/ㄴ댔자 structure can help you articulate situations where a desired outcome isn't achieved due to a counterproductive action.
This can be a particularly useful tool in highlighting the consequences of actions in conversations.