He promoted his own welfare at the expense of others.

他不惜以他人利益为代价换取自己的利益。

youdao

An entity, such as a baboon, is said to be altruistic if it behaves in such a way as to increase another such entity's welfare at the expense of its own.

如果一个实体，例如狒狒，其行为的结果是牺牲自己的利益，从而增进了另一同类实体的利益，该实体就被认为是利他性的。

youdao

An entity, such as a baboon, is said to be altruistic if it behaves in such a way as to increase another such entity "s welfare at the expense of its own."

如果一个实体，例如狒狒，其行为的结果是牺牲自己的利益，从而增进了另一同类实体的利益，该实体就被认为是利他性的。

youdao

As a result, John Dark, who farms at Mullion, has to undertake a 25-mile trip to market in Truro, meaning extra expense and increased concerns about animal welfare.

BBC: Livestock markets in decline

For wealthy countries, welfare states acted as a buffer to the economic shock, even at the expense of growth.

FORBES: PIGS Provide Cautionary Tale For U.S. Reform

Veronica King, NUS vice president for welfare, said she was not surprised more students were studying closer to home considering the "huge expense" of rent and bills on top of tuition fees and other basic living costs.

BBC: NEWS | UK | Education | Students 'stay home to cut costs'