devil-may-care attitude

devil-may-care attitude and devil-may-care manner (a very casual attitude; a worry-free or carefree attitude) — наплевательское отношение; легкомысленное отношение; пофигизм
I-couldn’t-care-less attitude

Example 1: You'd better get rid of your devil-may-care attitude if you want to succeed.

Example 2: Employers won't hire people with a devil-may-care attitude.