The Rothenberg Political Report says nearly 99% of House incumbents won their primary elections this year. In fact, the total figure is 98.6% of those who have been forced into primaries prevailed.
Even though ties to Washington can be a liability for Members, other advantages of incumbency, such as higher initial name identification and easier fundraising, can more than offset the liabilities. Popular disapproval of Congress doesn't mean that voters are ready to take out their anger on all incumbents.
Of course at least five dozen House incumbents are vulnerable in the general election, and majority of them could lose. But most of them will lose because of how their partisanship and voting records mismatches with their district -- not simply because they are current members of Congress.