Setting aside gerrymandering (which is a huge issue), the reelection rate doesn't tell the whole story. By what margin are House candidates typically winning? I'm sure there are plenty of landslides, but also lots of districts that were decided by a few percent -- and those who don't vote could be a deciding factor in those races if they chose to vote.

Or if we analyze this from an opportunity cost perspective, IMO voting is always the right choice. Maybe there's an 80% chance your vote "doesn't matter", but the cost is only 15 minutes of your time every 2 years. Isn't the 20% worth the risk? (OK, I am lucky enough to live in a state where voting lines are short. I understand it takes more than 15 mins for some people.)