the.com/vicious cycle

means A chain of events in which each problem causes the next, looping back to make the original problem worse, with no natural exit point.

from From logic and philosophy's 'circulus vitiosus' (Latin for 'vicious circle'), originally a term for a flawed argument that secretly assumes the very thing it's trying to prove, chasing its own tail in a loop of reasoning. The phrase migrated from debate halls into everyday speech, where 'vicious' kept its older sense of 'flawed' or 'corrupt' rather than 'cruel' — a circle that's vicious not because it bites, but because it's broken in a way that only loops back on itself. 'Cycle' eventually elbowed out 'circle' in casual use, likely for its ring of ongoing repetition.