Some previously despised minority groups, such as Asian immigrants, have not only broken the self-perpetuating cycle, they've gone so far out of its orbit that their population in universities are actually being actively limited by these policies.
Given that affirmative action is by some accounts responsible for higher university drop-out rates in target minorities, are you sure (I'm presuming you support the argument you're forwarding, my apologies if you're merely presenting it as an alternative line of argument raised by those who support the policies) that such policies aren't merely reinforcing the self-perpetuating cycle?
As I understand it, the change in peoples' view of Asian immigrants is partly because the immigrants have changed. A greater proportion of recent Asian immigrants to the US (compared with early waves of Asian immigrants) were of high socioeconomic status in their home country, and are coming for professional careers or to go to school, rather than to be factory or other low-status workers.
(And depending on how you define caught in the cycle, the descendants of early Asian immigrants might still be - even if race isn't against them anymore (which it might be in some cases - I don't know), social mobility is still difficult.)
Related: Heuristics for Evaluating the Soundness of the Academic Mainstream, Admitting to Bias, The Ideological Turing Test