Not sure what those 8 percent are thinking. They probably aren’t.
Of course, talk is cheap. The very same people who so loudly disapprove of Congress have re-elected 94 percent of its incumbents the last two election cycles. The last time it was as low as 90 percent was 1992.
People do seem to want change. They just rarely vote for it.
Inertia Wins! 
For all that people distrust Congress as an institution, they often like their congressman. Until Americans more often connect their individual congresscritters to the failures of the legislature in general, the incumbency rate will continue at its depressing heights.