Self-defeating

This is a difficult responsibility to embrace. For human history has often been a record of nations and tribes subjugating one another to serve their own interests. Yet in this new age, such attitudes are self-defeating.

Source: tatoeba (376953)

To target these young people is wrong – because they have done nothing wrong. It is self-defeating – because they want to start new businesses, staff our labs, serve in our military, and otherwise contribute to the country we love. And it is cruel.

Source: tatoeba (6292030)

Cutting off your nose to spite your face is self-defeating.

Source: wiktionary

[...] to make commuter operations profitable, a 70 per cent fare rise would be necessary. The president admitted that an increase of this magnitude would be self-defeating and suggested that the commuter himself should not have to bear the whole burden because the service was not exclusively for his benefit, but largely for that of the community concerned.

Source: wiktionary