διαφθείρειν τὰ πράγματα

From LSJ

αὐτόχειρες οὔτε τῶν ἀγαθῶν οὔτε τῶν κακῶν γίγνονται τῶν συμβαινόντων αὐτοῖς → for not with their own hands do they deal out the blessings and curses that befall us

Source

Greek > English (Woodhouse)

ruin one's prospects