God brought their days to an end in futility.

When they didn’t believe in God and didn’t trust in His salvation (Ps. 78:22)

and still continued to sin against Him and to rebel against Him and put Him to the test

by demanding the things they craved (vv. 17-18), and don’t abandon their greed (v. 30) and kept on sinning

(v. 32, God would bring their days to an end in futility and their years in terror (v. 33).